Fixed `maxRange` calculation for 2x2 player units

[Meridian]

Fixed in OXC nightly build 2021-02-26; and in OXCE v7.0.

The maxRange for 2x2 units was calculated only around the "main" tile of a 2x2 unit.
Now all tiles of a 2x2 unit are considered.

Attached picture illustrates the change:
- pink color = 2x2 unit
- pink and green color = range 1 around the unit
Old behavior on the left, new on the right.