remove whitespace
Updated Code docs
Merge pull request #1835 from jwarwick/code_docs

Updated Code docs
fix wrong error message for `nil.func()` call

The expected behavior for `nil.func()` should be:

    iex(1)> nil.test()
    ** (UndefinedFunctionError) undefined function: nil.test/0
       nil.test()

Also via cli `elixir -e`:

     $ elixir -e 'nil.test()'
     ** (UndefinedFunctionError) undefined function: nil.test/0
     nil.test()
     ....

Undefined function calls behave like:

    iex(1)> hello()
    ** (RuntimeError) undefined function: hello/0
Merge pull request #1834 from tonini/fix-wrong-error-message

fix wrong error message for `nil.func()` call
Add Kernel.LexicalTracker
Move lexical tracker to scope
Add warnings for unused aliases
Add tests for LexicalTracker
Simplify current module macro handling
Avoid interpolation which would convert char lists twice
Do not write manifest down if there was a compilation error, closes #1833
Add typespecs and to_string conversion to some IO APIs
Document side-effects on stream APIs
Get rid of useless fourth argument in defexception
Remove unused alias
Update CHANGELOG