The `each_line` function in `ReaderUtil` acts very differently to equivalent functions in Python, Ruby, Clojure etc. E.g. given a file `t` with contents `trailing\nnew line\n` and `n` containing `no trailing\nnew line`:

Rust:
```Rust
t: ~[~"trailing", ~"new line", ~""]
n: ~[~"no trailing", ~"new line"]
```

Python:
```Python
>>> open('t').readlines()
['trailing\n', 'new line\n']
>>> open('n').readlines()
['no trailing\n', 'new line']
```

Ruby:
```Ruby
irb(main):001:0> File.readlines('t')
=> ["trailing\n", "new line\n"]
irb(main):002:0> File.readlines('n')
=> ["no trailing\n", "new line"]
```

Clojure
```Clojure
user=> (read-lines "t")
("trailing" "new line")
user=> (read-lines "n")
("no trailing" "new line")
```

The extra string that rust includes at the end is inconsistent, and means that it is impossible to distinguish between the "real" empty line a file that ends `...\n\n`, and the "fake" one after the last `\n`.

The code attached makes Rust's `each_line` act like Clojure (and PHP, i.e. not including the `\n`), as well as adjusting `str::lines` to fix the trailing empty line problem.

Also, add a convenience `read_lines` method to read all the lines in a file into a vector.

I made a typo in `str::levdistance` in my str pull request. This fixes it.

Specifically, `lines` and `each_line` will not emit a trailing empty string
when given "...\n". Also, add `read_lines`, which just collects all of
`each_line` into a vector, and `split_*_no_trailing` which will is the
generalised version of `lines`.

Closes #5411.

Closes #4468

r? @catamorphism

This makes the `trim` and `substr` functions return a slice instead of an `~str`, and removes the unnecessary `Trimmable` trait (`StrSlice` already contains the same functionality).

Also moves the `ToStr` implementations for the three str types into the str module in anticipation of further untangling.

In struct section of tutorial, make everything more coherent and
clear by always using "struct Point".
Also, do not prematurely introduce pointers and arrays.
Fixes #5240

Closes #4468

librustc: Forbid destructors from being attached to any structs that might contain non-Owned fields. r=nmatsakis

The old string benchmarks weren't very useful because the strings weren't long enough, so I just threw those out for now. I left out benchmarks of `oldmap` because it's clear that it's 30-40% slower and it doesn't implement the `Map` trait.

This also cleanly divides up `insert`, `search` and `remove`.

Adds an assert_eq! macro that asserts that its two arguments are equal. Error messages can therefore be somewhat more informative than a simple assert, because the error message includes "expected" and "given" values.

Switched over substr and trim functions in str to be non-allocating, temporary renamed them to better track use-sites

* Closes #4603

In struct section of tutorial, make everything more coherent and
clear by always using "struct Point". Also, do not prematurely
introduce pointers and arrays. Fixes #5240
Signed-off-by: NLuca Bruno <lucab@debian.org>