Add invalid coord variables
Add invalid statics for game types as well
Various work towards a basic game implementation

Get rid of some virtual functions that weren't needed.
Fix some functions to work during static init if need be.
Units now have unique incremental IDs
Framework for movement and action orders, plus some better organisation of the test code
Even more tests
use uvec unstead of two params, simplifies things
remove unit inheritence, twas a silly idea, and remove usage of shared ptr and unique ptr not needed anymore