Yet another fix for URLs within the CSS value matching
Issue 4536 (Cache options)
http://code.google.com/p/fbug/issues/detail?id=4536

Part 1: Replaced all preference usages within the global Firebug scope
by calls to Options.get() and Options.set()
Issue 4536 (Cache options)
http://code.google.com/p/fbug/issues/detail?id=4536

Part 2: Cached the preferences within a Map
Issue 4536 (Cache options)
http://code.google.com/p/fbug/issues/detail?id=4536

Part 3: Adjusted FBTests to use Options.get() instead of directly
accessing the preferences via the global Firebug scope
Fixed broken merge