Publish the "Caching with Rails" guide

Inform user to add styles in correct location in application.css

[ci skip]

Before this patch, using `bin/rails test` with a non existing
file or directory argument would silently swallow the argument and
run the whole test suite.

After the patch the command fails with `cannot load such file --`.

Add missing assertion for test_route_with_colon_first

Update Time#advance documentation with examples [ci skip]

Fix ambiguous argument warning

encapsulate all arguments

Use #start_with? and #[] for speed

Save a string allocation inside loop

In the `tag_options` method, strings are continuously added to the
`output` string. Previously, we concatenated two strings and added the
generated string to `output`. By adding each of the strings to
`output`, one after the other, we will save the allocation of that
concatenated string.

Benchmark:

    require 'benchmark/ips'

    sep = " ".freeze

    Benchmark.ips do |x|
      x.report("string +") {
        output = ""
        output << sep + "foo"
      }
      x.report("string <<") {
        output = ""
        output << sep
        output << "foo"
      }
      x.compare!
    end

Results (Ruby 2.2.2):

    Calculating -------------------------------------
                string +    88.086k i/100ms
               string <<    94.287k i/100ms
    -------------------------------------------------
                string +      2.407M (± 5.8%) i/s -     12.068M
               string <<      2.591M (± 7.0%) i/s -     12.917M

    Comparison:
               string <<:  2591482.4 i/s
                string +:  2406883.7 i/s - 1.08x slower

While the readability may be slightly worse, the speed improvement is
significant: Twice as fast when there's no leading "/" to remove, and
over 4 times as fast when there is a leading "/".

Benchmark:

    require 'benchmark/ips'

    def match(controller)
      if controller
        if m = controller.match(/\A\/(?<controller_without_leading_slash>.*)/)
          m[:controller_without_leading_slash]
        else
          controller
        end
      end
    end

    def start_with(controller)
      if controller
        if controller.start_with?('/'.freeze)
          controller[1..-1]
        else
          controller
        end
      end
    end

    Benchmark.ips do |x|
      x.report("match") { match("no_leading_slash") }
      x.report("start_with") { start_with("no_leading_slash") }

      x.compare!
    end

    Benchmark.ips do |x|
      x.report("match") { match("/a_leading_slash") }
      x.report("start_with") { start_with("/a_leading_slash") }

      x.compare!
    end

Result (Ruby 2.2.2):

    Calculating -------------------------------------
                   match    70.324k i/100ms
              start_with   111.264k i/100ms
    -------------------------------------------------
                   match      1.468M (± 7.1%) i/s -      7.314M
              start_with      3.787M (± 3.5%) i/s -     18.915M

    Comparison:
              start_with:  3787389.4 i/s
                   match:  1467636.4 i/s - 2.58x slower

    Calculating -------------------------------------
                   match    36.694k i/100ms
              start_with    86.071k i/100ms
    -------------------------------------------------
                   match    532.795k (± 4.7%) i/s -      2.679M
              start_with      2.518M (± 5.8%) i/s -     12.566M

    Comparison:
              start_with:  2518366.8 i/s
                   match:   532794.5 i/s - 4.73x slower

correct example of button_tag [ci skip]

wrapper div has been removed in cbb91745

PostgreSQL is strict about the usage of `DISTINCT` and `ORDER BY`, which
one of the tests demonstrated. The order clause is never going to be
relevant in the query we're performing, so let's just remove it
entirely.

Add #cache_key to ActiveRecord::Relation.

[ci skip]

Add descriptions about `ActiveRecord::Base#to_param` to

* `ActionDispatch::Routing::Base#match`
* Overriding Named Route Parameters (guide)

When passes `:param` to route definision, always `to_param` method of
related model is overridden to constructe an URL by passing these
model instance to named_helper.

This is a follow up to #21008.

Add documentation to get a running custom base controller [ci skip]

Fix WARNINGS flag inside guides/Rakefile

Don't fail when checking dependencies in bin/setup script

Array#any? is slower and not the inverse of Array#empty?

```
empty_array = []
small_array = [1] * 30
bigger_array = [1] * 300

Benchmark.ips do |x|
  x.report('empty !empty?') { !empty_array.empty? }
  x.report('small !empty?') { !small_array.empty? }
  x.report('bigger !empty?') { !bigger_array.empty? }

  x.report('empty any?') { empty_array.any? }
  x.report('small any?') { small_array.any? }
  x.report('bigger any?') { bigger_array.any? }
end
```

```
Calculating -------------------------------------
       empty !empty?   132.059k i/100ms
       small !empty?   133.974k i/100ms
      bigger !empty?   133.848k i/100ms
          empty any?   106.924k i/100ms
          small any?    85.525k i/100ms
         bigger any?    86.663k i/100ms
-------------------------------------------------
       empty !empty?      8.522M (± 7.9%) i/s -     42.391M
       small !empty?      8.501M (± 8.5%) i/s -     42.202M
      bigger !empty?      8.434M (± 8.6%) i/s -     41.894M
          empty any?      4.161M (± 8.3%) i/s -     20.743M
          small any?      2.654M (± 5.2%) i/s -     13.256M
         bigger any?      2.642M (± 6.4%) i/s -     13.173M
```

Ref: https://github.com/rails/rails/pull/21057#discussion_r35902468

Beyond Ludicrous Speed

It is slightly faster:

```
Calculating -------------------------------------
        each; delete    35.166k i/100ms
           delete_if    36.416k i/100ms
-------------------------------------------------
        each; delete    478.026k (± 8.5%) i/s -      2.391M
           delete_if    485.123k (± 7.9%) i/s -      2.440M
```

We don't always need an array when generating a url with the formatter. We can be lazy about allocating the `missing_keys` array. This saves us:

35,606 bytes and 889 objects per request

THe only reason we were allocating an array is to get the "missing_keys" variable in scope of the error message generator. Guess what? Arrays kinda take up a lot of memory, so by replacing that with a nil, we save:

35,303 bytes and 886 objects per request

In the `tag_options` method an array is used to build up elements, then `Array#*` (which is an alias for `Array#join` is called to turn the array into a string. Instead of allocating an array to build a string, we can build the string we want from the beginning.

Saved: 121,743 bytes 893 objects

We can save a few objects by freezing the `replacement` string. We save a few more by down-casing the string in memory instead of allocating a new one. We save far more objects by checking for the default separator `"-"`, and using pre-generated regular expressions.

We will save 209,231 bytes and 1,322 objects.

If we don't mutate the `recall` hash, then there's no reason to duplicate it. While this change doesn't get rid of that many objects, each hash object it gets rid of was massive.

Saves 888 string objects per request, 206,013 bytes (thats 0.2 mb which is kinda a lot).

Instead of calling `sub` on every link_to call for controller, we can detect when the string __needs__ to be allocated and only then create a new string (without the leading slash), otherwise, use the string that is given to us.

Saves 888 string objects per request, 35,524 bytes.

Saves 888 string objects per request.