add 'guard' lines to .bash_profile to detect modification
Merge remote-tracking branch 'upstream/master'
if X11 available, use it
quote $SSH_CLIENT in prompt test.

use "command -v" instead of "-x `which …`" to see if something exists. see: http://stackoverflow.com/questions/592620/check-if-a-program-exists-from-a-bash-script
Merge pull request #4 from srl295/master

Misc improvements