Improve description of operations that takes linear time
Update doc for GenEvent.stream/2

- GenEvent streams are not two way, so remove language suggesting that
you can notify via the streams.
- Clarify that consumption doesn't start until we enumerate.
Merge pull request #2539 from hamiltop/update_genevent_stream_doc

Update doc for GenEvent.stream/2
Call Mix.start, Mix.CLI.main directly in bin\mix.bat
Remove non-existing from argument from handle_cast

`handle_cast` does not support a `from` argument and this example will crash if it has one.
Merge pull request #2544 from eproxus/patch-1

Remove non-existing from argument from handle_cast
Merge pull request #2541 from chyndman/mix-bat-exec-directly

Call Mix.start, Mix.CLI.main directly in bin\mix.bat
Ensure all elixir dependencies are started before hand, closes #2542
Added Map.from_struct/1

Signed-off-by: José Valim <jose.valim@plataformatec.com.br>
Also allow structs atoms on Map.from_struct/1
Remove invalid return values from GenEvent.handle_info/2 docs
Do not traverse the string twice in String.slice(<str>, <range>)

Signed-off-by: José Valim <jose.valim@plataformatec.com.br>
Clean up String.slice/2/3 impls
Update CHANGELOG
Use john and meg in code samples
No longer allow empty access as in [][]