Unit upkeep independent of homecities

[SMACX2]

Added some more information on civ 3/4 behavior in the first post.

Some additional ruleset tags for defining a "free unit support cap" like in civ 3/4 would be necessary to circumvent the homecity mechanism.

[SMACX2]

Currently units without a homecity do not pay upkeep even if they have gold upkeep which is paid globally.

I suggest that gold upkeep for units is always paid, no matter if they have a homecity or not.