Static planetinfo

This seems - eventually - to be working again. Please test it and report any errors: this is a huge change (even not counting the 80,000 lines of planetinfo.plist) and there may well be some bugs in there.

Things that seem to work:
* [x] flying around, charts, F7 screen, planet texturing
* [x] galactic witchspace
* [x] OXP setting of planetinfo (including removal when the OXP goes)
* [x] JS setting of planetinfo (including changing layer)
* [x] layers
* [x] nova mission results preserved
* [x] loading 1.80-era savegames

Still to do:
* [x] get the system manager to process secondary planet definitions properly
* [x] move the rest of the odd properties out of planetinfo.plist into a gamesettings.plist
* [x] update some loading/processing of properties
* [ ] resave the starting scenarios files into the new save game format (though this is more a task for shortly before release)
* [x] validate data types before setting a value 
* [ ] Xcode update to include the `OOSystemDescriptionManager` files (and possibly cleanup of build errors/warnings that gcc ignores)
* [x] Test the nova mission still works

Known compatibility issues:
* OXPs which make changes by JS but don't check to remake them will have those changes disappear on loading a 1.80 save game. If they remake the changes they should stick properly, though.
* OXPs which make changes by legacy script will not be able to save those changes to the save game
* Save games from this branch __will not load__ in 1.80 (or in 1.81) - not just losing data. A few days advance notice on the forums before we merge it is going to be essential to let people get away from the nightly builds and/or take backups.