Add a test for mix config files
Add iodata_to_binary and chardata_to_string to IO
Add String.to_char_list and List.to_string
Make deprecations compiler warnings
Merge pull request #2288 from ericmj/compile-deprecations

Make deprecations compiler warnings
Optimize cond expansion
Move List and String deprecations to new mechanism
More deprecations around tuples and records
Move Integer/Float conversions to their respective modules
Get rid of BitString module and bitstring conversions
Move binary and list conversions to String and List
Update CHANGELOG
Reduce examples of disabling macros hygiene
Fix ExUnit.DocTest docs
Merge pull request #2292 from mururu/fix-doc_test-docs

Fix ExUnit.DocTest docs
Update record.ex docs, closes #2291
fix Enum.join for empty elements in the begining of the collection
Merge pull request #2293 from liveforeverx/fix_enum

fix Enum.join for empty elements in the begining of the collection
Add Macro.prewalk/2/3 and Macro.postwalk/2/3
Do not allow nil context to be set on quote