Added Facebook Bot Filter. Untested.
Added isBot method.

Code is from user diem-project, commit number
1381e1674c57e4f574efc2c2bfa29db76eb56134 of 2011-09-06, which was
forked and modified, but never merged back into  the main repo.
Expanded list of known bots.
Merge remote-tracking branch 'eightygrit/master'

Conflicts:
	lib/phpUserAgentStringParser.php