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
Remove warning from new applications
Allow h +/1 as valid syntax