Inspired by https://github.com/rails/rails/commit/931ee4186b877856b212b0085cd7bd7f6a4aea67

```ruby

def stat(num)
  start = GC.stat(:total_allocated_object)
  num.times { yield }
  total_obj_count = GC.stat(:total_allocated_object) - start
  puts "#{total_obj_count / num} allocations per call"
end

h = { 'x' => 'y' }

stat(100) { h.     each { |pair| pair } }
stat(100) { h.to_a.each { |pair| pair } }

__END__
1 allocations per call
2 allocations per call
```

Form full URI as string to be parsed in Rack::Test.

There are performance gains to be made by avoiding URI setter methods.

Fixed a problem where `sum` used with a `group` was not returning a Hash.

Most recent change should be moved to the top

Documentation: Rename Posts to Articles

Move extract_scale to decimal type

Move PG OID types to their own files

so tht I don't go totally insane with THsi crazy hash driven
development. why is Everything a hash? Why do people think hashes in
hashes with random keys is a Good API? You can't find things or
deprecate them or control access whatsoever, you just have to hope that
everyone is like "oh, you want to change that? that's cool! we all know
it's hashes so go for it!"

The End.

The only type that has a scale is decimal. There's a special case where
decimal columns with 0 scale are type cast to integers if the scale is
not specified. Appears to only affect schema dumping.

The optimized and non-optimized path share more code now without
significant performance degretation

Example:

x = [1,2,3,4]
y = [3,2,1]

def test x, y
  hash = {}
  x.zip(y) { |k,v| hash[k] = v }
  hash
end

def test2 x, y
  Hash[x.zip(y)]
end

def test3 x, y
  x.zip(y).each_with_object({}) { |(k,v),hash| hash[k] = v }
end

def stat num
  start = GC.stat(:total_allocated_object)
  num.times { yield }
  total_obj_count = GC.stat(:total_allocated_object) - start
  puts "#{total_obj_count / num} allocations per call"
end

stat(100) { test(x,y) }
stat(100) { test2(x,y) }
stat(100) { test3(x,y) }

__END__
2 allocations per call
7 allocations per call
8 allocations per call

Fix typo guides/source/active_support_instrumentation.md [ci-skip]

fixes in active record query for reorder in rails guides

Rename `oid_type` to `cast_type` to make PG columns consistent with abstract columns

Add missing nodoc

Fix serialized field returning serialized data after update_column

Conflicts:
	activerecord/CHANGELOG.md

This reverts commit 9a1abedc, reversing
changes made to c72d6c91.

Conflicts:
	activerecord/CHANGELOG.md
	activerecord/test/models/comment.rb

This change break integration with activerecord-deprecated_finders so
I'm reverting until we find a way to make it work with this gem.

fix formatting and text for ActionController::Redirecting doc

As we promote these classes to first class concepts, these classes are
starting to gain enough behavior to warrant being moved into their own
files. Many of them will become quite large as we move additional
behavior to the type objects.

  - `extract_precision`, `extract_limit`, and `extract_default` probably need to follow.
  - would be good to remove the delegation `Column#extract_scale`.

/cc @sgrif