Improved preferences

Tweak.xm
Made DEBUG macro into key within preferences file but no configuration
interface to change it. Added preferences file creation upon first
launch after install.

BCPreferences.mm
Changed all references to "prefs" into "BCPreferencer" to prevent
conflict with any other package using the same unidentifiable name for
the preference bundle. Removed redundant developer method.

BCPreferences/Resources/BCPreferences.plist
Reorganized and cleaned configuration pane, leaving the essential items:
general switch and blacklist.