Format EXIT signals consistently
Mention ERL_COMPILER_OPTIONS and rename ELIXIR_ERL_OPTS to ELIXIR_ERL_OPTIONS

Closes #2271
Merge pull request #2270 from fishcakez/format_banner_EXIT

Format EXIT signals consistently
Update exit signals in Exception to {:EXIT, pid}
List all soft deprecations that have become deprecated
Merge xgen and soft deprecate existing behaviours
Rename some Makefile targets. Closes #2274

kernel -> core
test_kernel -> test_stdlib
Merge pull request #2275 from alco/makefile-rename-kernel

Rename some Makefile targets. Closes #2274
core -> stdlib in makefile
Properly handle non-boolean values for boolean options
Add more sanity-check tests for OptionParser
Don’t ignore values for ‘--no-*’ options
Format OptionParser tests more nicely
Fix unused variable warning
Remove unused import in elixir_translator.erl
Merge pull request #2277 from alco/elixir-translator-warning

Remove unused import in elixir_translator.erl
Merge pull request #2276 from alco/option-parser-fix

Option parser fix
Better docs and tests for Keyword.update and Keyword.update!
Small doc fixes for Keyword
Merge pull request #2279 from alco/keyword-doc-fixes

Keyword doc fixes