Enhancements

[Elixir] Support Erlang 17.5 and 18.0
[Mix] Support "--search PATTERN" in "mix help"
[Mix] Support :start_permanent that starts the application as permanent
[Mix] Support :build_embedded that compile protocols, avoid symlinks and ensure protocols are loaded on boot
[Mix] Make "mix app.start" public and support "--permanent" and "--temporary" options
[URI] Speed decoding operations

Bug fixes

[Elixir] Produce clearer error messages for syntax errors before a sigil
[Elixir] Return value when matching on _ in the last line of a block
[Elixir] Ensure changes in child deps forces the parent to recompile
[Kernel] Fix a bug where =~/2 returned false when matching on an empty string. The current behaviour was changed to match the behaviour of String.contains?/2
[Mix] Store relative paths in erlang manifests
[Mix] Fix httpc proxy option profile for downloading hex and other safe packges
[Mix] Fix missing behaviour warning when compiling Erlang modules