Switched launchers to execute via "/bin/sh" rather than "bash"

Using bash was a bit heavy-handed when all I really want is a /bin/sh -c
just like popen()/system().  On some systems this won't make any
difference, but on Debian /bin/sh -> dash.
Reflowed keystroke section of README to 75 wide, mostly for the github UI.
Automatically "autoconf" screen-sized new windows as "allscreened"

This enables automagic mplayer -fs borderless fullscreened playback windows
with minor additions to the code.  Previously one had to focus the playback
window and mod1-triple-k it to lose the borders, now it "just works".
Merge branch 'master' into ph1l
Merge remote-tracking branch 'upstream/auto_allscreen' into ph1l