Patch v1.12

MOD: docking at stations now requires hostile ships to be 3 tiles away instead of 2
FIX: hostile ship range calculation for docking at station now adjusts for the fact that you can sometimes move and then dock in the same turn in 'manual' weapons mode
FIX: bug where union defector sometimes does not appear in the specified target sector
FIX: null reference exception causing varied strange behaviour when loading games (introduced in v1.11)
FIX: bug occasionally creating invisible ships