Merge pull request #2772 from pdericson/master

fix example sample.ex -> sample.eex
Do not require {ref, :done}, instead allow sync removal
Add U as ungreedy option, soft deprecate r
Allow U (upper case u) as an option for sigil_r
Fix a typo in Dict's docs
Load dependencies before deps.check compiles
Add tests for add_process_handler/2
default ports for WebSocket
Merge pull request #2776 from rbaier/uri-ws

Default ports for WebSocket
Merge pull request #2775 from budstein/patch-2

Fix a typo in Dict's docs
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