Add a pair of even and odd checking functions.
Merge pull request #1629 from Raynes/is_it_even_odd

Add a pair of even and odd checking functions
import accept :functions and :macros as values in :only

This commit removes the previous ambiguous syntax:

    import :functions, Foo

In favor of:

    import Foo, only: :functions
Print failures for ExUnit as soon as they come
Update CHANGELOG
Deprecate to_binary in favor of to_string

We also rename Binary.Chars to String.Chars.

As Binary.Chars was the protocol used for interpolation,
it is semantically correct to have a protocol that works
on strings, instead of raw binaries.
Update CHANGELOG
Properly order CHANGELOG
Handle when :file.get_cwd returns a binary
Another attempt at cwd handling