[PRPL][Suggestion] GrowStruc vs MireLand discrepancy

[planetfall]

The GrowStruc command pushes to the stack whether the struc had room to grow. The MireLand command does not return whether the mire grew.

Suggestion 1:
Make MireLand push 1 to the stack if there was an unmired cell available.

Suggestion 2 (I'd prefer this one for the increased flexibility):
Make GrowStruc not return anything, and add IsStrucFullyGrown and IsLandFullyMired calls.