Engine drag cubes part 3

[DMagic1]

Custom drag cubes for 1.25m, 2.5m and 3.75m engines:
LV T-30 & LV-T45 & Vector
Mainsail & Skipper
Rhino

All drag cubes adjusted so that compact variants used in the middle of a large stack, or on the end of a smaller stack behave more like expected.

This has relatively little effect on engines placed at the bottom of a large stack. For instance, the compact variant of the Mainsail or Skipper placed at the bottom of a 2.5m stack behaves about the same as before, but the compact variant of either engine performs better when placed in the middle of a 2.5m stack, or the end of a 1.875m/1.25m stack, respectively.

The "Boat Tail" variant drag cubes are mostly unchanged.

[ChrisAdderley]

Merged, thanks!