Fix SupervisorTest :push handle_cast method

* handle_cast/2 does not take 'from' param
Merge pull request #2878 from akira/supervisor_test_fix

Fix SupervisorTest :push handle_cast method
Move 0 index match to the function head in `String.split_at/2`
Move same pos match to the function head in `Regex.apply_list/5`
Merge pull request #2879 from lexmag/move-to-fun-heads

Move guards to fun heads
rename two identical variables to same name and remove guard
Merge pull request #2881 from jw2013/string

rename two identical variables to same name and remove guard
Make IO.ANSI.Docs readable on white background

The `default_options` for `IO.ANSI.Docs` uses bright yellow for
documentation headers and titles.

This is very nice and readable when using a terminal with a dark
background. However, when using a terminal with a bright (e.g. white)
background, those parts are unfortunately illegible.

This patch removes the `:bright` part from the `default_options`, to
make the defaults better suited to more people.
Merge pull request #2882 from Frost/no-more-bright-yellow-in-ansi-docs

Make IO.ANSI.Docs readable on white background
correcting broken url in GenEvent docs
Merge pull request #2884 from sammyt/fix/genevent-docs

correcting broken url in GenEvent docs
fix wrong CRLF grapheme
Don't show hex update message on mix local.hex
fix broken link in GenServer module
Merge pull request #2887 from jw2013/404

fix broken link in GenServer module
Merge pull request #2886 from jw2013/CRLF

fix wrong CRLF grapheme
Add doctest to the test template

Signed-off-by: Mikhail S. Pobolovets <styx.mp@gmail.com>
Merge pull request #2889 from styx/add_doctest_to_mix_new_test_template

[MIX] Add doctest to the test template
Make map_reduce @spec stricter

Signed-off-by: Mikhail S. Pobolovets <styx.mp@gmail.com>
Merge pull request #2890 from styx/more_strict_spec_for_map_reduce

Make map_reduce @spec stricter