Object Library

[Luis Carvalho]

Hello everyone!

I was getting nervous of having too much uncommitted code in my PC, so I 
committed the current library to CVS.

In short:
	* The library browser follows Andreas' suggestions (i hope :))
	* Added a new constructor to PMPart that doesn't create any widget (this is 
not perfect, looks more like a hack.
	* Library Object editing is done using drag and drop
	* Added a library handle wich should allow us to handle indexes and searches 
better (but not yet)

What is missing:
	* Handling external files i.e. density files, bump maps or other bitmaps
	* The file names are temporary names to avoid namespace clashes (I must 
revisit this, as it's not very pretty, either library_index.xml hides this or 
the way the names are generated will have to change)
	* No delete on the object tree of the library. I can't understand why, yet
	* Drag to a valid position that causes insert errors deletes the objects from 
the source of the drag. This is associated with PMTreeView's problem 
described in the TODO.
	* Visual feedback when the current library object is editable
	* Libraries can't have sub directories
	* There is a crash associated to changing the preview image. Still tracking 
it down.

Andreas,

I still expect to finish the library before 3.2. Anyway, if it's not ready by 
then it's very easy to disable fully, that's why I wasn't very worried about 
this unstable commit.

Regards,
Luis