developing in progress for:
* check erlang files and dependencies before compiling
* error output for erlang compiling
* compiling of leex and yecc
Add HashDict.t type
Drop HashDict.t type and spec HashDict.new with Dict.t
Pick latest variable in between clauses instead of picking a random one
Push a test case related to the nested vars in clauses
Default mix task should be run, closes #834
Fix invalid bit syntax in docs.
Misc. documentation cleanup
Fix typo in IEx.Helpers.h/1
Merge pull request #841 from happy4crazy/iex-helpers

Tiny typo in IEx.Helpers.h/1
Suppress minor warning (unused variable) in hash_dict.ex
Doc typos, misc. style cleanup
Merge pull request #842 from happy4crazy/doc-fixes

Kernel doc fixes
Merge pull request #776 from liveforeverx/compile-erl-new

WiP for compiling of erlang/leex/yecc source files
Only accept the IO device on inspect when we have three args
Small refactoring on Mix tasks
Update CHANGELOG
Fix bug when running mix on directories containig space, closes #840
Switches are now overridden by default but can be kept in order if chosen, closes #782
Backwards incompatible change on `before_compile` and `after_compile`

Both callbacks now receive the environment as
first argument instead of the module.