Resolves #830 - ghost_form is only selectable by members.

ghost_form is now saved with other preferences.
Public visibility of memberships is toggable and saved with other preferences.
ooc-colors for admins and members are now sanitized. Bright colours like Yellow, white and baby-blue will be darkened for the sake of legibility.
Related to above - added helper procs to convert between RGB and HSL colour models.
Admins cannot modify var/unlock_content without +DEBUG rights. unlock_content moved from client into prefs.

Player savefile version number updated - this will trigger savefile updates, no data should be lost.