Make explicit is_range / is_regex are allowed in guards
Limit the allowed sigils
Remove uneeded mix fixtures
Allow operators to be captured, example: &+/2
Move from  // to \\
Deprecate usage of @behavior in favor of @behaviour
Address undefined macro if on bootstraping
Improve error messages for bad arity errors
Deprecate =~

Use String.contains?/2 when the right side is a string or
String.match?/2 when the right side is a regex.

The goal of this deprecation is to make space for the upcoming
`~` and `~=` operators.
Generalize unary operators followed by int have higher precedence
Fix list with keywords expansion

The list `[1, 2, three: :four]` now correctly expands
to `[1, 2, {:three, :four}]`.
IEx now loads the .iex.exs file instead of the .iex one
Remove Unix specific behaviour from File.cp/3 and File.cr_r/3

Previously those functions would behave as in their Unix counterpart
where copying behaved differently depending if the destination was
an existing directory or not. We have explicitly disallowed this
behaviour and added the proper notes to the docs.

Closes #2024.
Fix fixtures copying on mix tests
Remove unecessary lexical check in parser
Add `Version.valid_requirement?/1`
Fix test in previous commit
Lexer's valid_required? can now be private
Revert "Deprecate =~"

This reverts commit e42e3e55ca1561fe56b58d6f51c7b0faae6a7a1e.
Remove m/0 helper

The goal is to come up with a general
IEx module for runtime statistics.