Refactor of pakset loading

[ceeac]

This patch centralizes the pakset loading code in a new pakset_manager_t class. Previously, this code was scattered across obj_reader_t, karte_t and ... log_t. In terms of functionality there should be no differences.

[prissi]

Why not? The inner working of the xrf and else stuff is still very magic, but having it in one place is probably a good idea.

I am a little unsure of the pak_mamanger source location, maybe it should rather should go into the descriptor folder?

If the location is determined, the installing and downloading of full paks should go here as well.

[prissi]

I think dataobj is probably indeed the best location. I will put the pakset installing there as well. Please submit

[ceeac]

Yes, IMO descriptor/should only contain the descriptors, readers and writers.
Submitted the patch in r10611.