Engine ratings on combat vehicles not automatically rounded up to a multiple of 5 for cost purposes

[assaultdoor]

With MML 0.47.4 on OS X, if a combat vehicle's mass * speed - suspension factor is not a multiple of 5, an incorrect value will show up in the Preview tab, and the engine's cost will be calculated incorrectly. Saving and reloading the unit appears to fix this.

So, for example, a 6-ton tracked vehicle with a speed of 6 is listed as having an 36 engine, and has a cost of 5000 * 36 * 6 / 75 = 14,400 c-bills. After saving and reloading, the vehicle has a 40-rated engine with the right cost.