#558 Public Access calendar configuration

[chris]

1) Offer option to disable category for Public Access calendar / non-logged in users (Currently the "cat_id" trick offers non-logged in users the possibility to simply change the ID # and browse whatever categories they wish) and to prevent "cat_id" trick from working. (VER 1.1.2)

2) option to force Public Access calendar to only show 1 category / deny ability to change.