Add U as ungreedy option, soft deprecate r
Allow U (upper case u) as an option for sigil_r
Merge pull request #2774 from jpb/regex-r-option-deprecation

Change Regex ungreedy option to U
Update CHANGELOG
Include stracktrace on ExUnit timeouts
Ensure Mix.Config is deep merged
Add compatibilty with OTP 18 typespec changes
Merge pull request #2777 from elixir-lang/emj-otp-18

Add compatibilty with OTP 18 typespec changes
Small fix for Application docs. Returning value is not a tuple
Merge pull request #2778 from pedrosnk/master

Small fix for Application docs. Returning value is not a tuple
Update release instructions
Change version requirement to be MAJOR.MINOR
Filter out :elixir_lexical from stacktraces
Improve GenEvent docs
Documented File.stat options
Merge pull request #2783 from bbense/documentation-tweaks

Documented File.stat options
Improve stat docs