mktemp’s template argument is required on OS X

And possibly others. Fixes #337.
Use gcc -std=c99 instead of c99 on OS X

Automatic checking in Makefile. Fixes #308 and #340.
Remove install note about OS X

Should work “out of the box” now. See #340.
Add play and pause commands

Add commands that always play and always pause, in addition to the
current toggle pause command.

Closes #342.
piano: Add error message for code 1039

See #352.
Stop playback if audio file is not accessible

See #352.
Transform actual station when loving/banning songs

Loving/banning a song from a shared station while playing quickmix
resulted in “call not allowed”, because we tried to transform the
quickmix instead of the song’s real station. Fixes #354.
Fix station name when deleting a station
Merge remote-tracking branch 'upstream/master'

Conflicts:
	src/settings.h
	src/ui_dispatch.h