Automatically download dependencies, if available, when installing OXZ

Dependencies already met won't be downloaded (e.g. if an OXZ depends on
ABC >= 0.4, and ABC 0.6 is installed, ABC 0.8 won't be automatically
downloaded)
Fix use of NSInteger as format argument
Fix use of OO_ENTER_OPENGL() in planetDrawable
Stop problems on ship library screen

Also fix bug with NPC shield booster removal
preserve scanner zoom across docking, witchspace and game saves
Merge remote branch 'upstream/master' into npc_reaction_times