Pan Update

Here's a new snapshot. I've made a lot of changes in this one.

• renamed pan-signals to pan-base-signals.
• altered some signals.
  
• when adding to cache make room if disk is full.
• updated flagset.[ch].
• added pan_g_ptr_array_(ref,unref) to ref/unref objects in g_ptr_array.
• converted /filters to use GObject.
• updated /rules.
• updated /identities.
• updated /dialogs.
• removed message-identifier.[ch].
• various related updates.

Since all the sub-directories compile, it's now time to work on the main code. I think I'll need to start with the tasks.

rev. 159