Merge branch 'hn/highlight-sideband-keywords'

The sideband code learned to optionally paint selected keywords at
the beginning of incoming lines on the receiving end.

* hn/highlight-sideband-keywords:
sideband: do not read beyond the end of input
sideband: highlight keywords in remote sideband output

diff --cc Documentation/config.txt
Simple merge

diff --cc help.c
Simple merge