Buffed repair speed for wheels, hover and cyborgs

[Monsterovich]

Rebased version of: #3705

Added the repairFactor field to propulsion. The idea is to increase the usefulness of wheels and hover in the game, at least in terms of repair speed.

If hover has some situational application, then wheels are hardly ever used.

[Raptor959]

I am on the fence with this change in that I don't think hover needs it at all and that it probably shouldn't be enabled from the games onset at it would probably have a massively disproportionate and negative effect on the early game when players only have wheels.

[Monsterovich]

and negative effect on the early game when players only have wheels

The problem is that wheels are discarded as soon as the player has better options. Even the usefulness of tracks is questionable in some cases. Wheels are useless in 100% of cases.

[Raptor959]

Well a non-insignificant portion of that is how for 7.5 minutes half-tracks are the only option for additional droid survivability until you research the first medium body, The other part is that it has bad damage resistances, no health bonus, and the speed advantage is a little too slim.
Those need to be adjusted for wheels to remain useful once half-tracks are available and this change would help keep such buffs subtle, However I think the repair speed buff for wheels and cyborgs should have a research requirement of some kind so that it comes into effect at ~7 minute mark.

[aubergineagain]

To make wheels useful for longer they should be faster on roads/concrete terrain?

https://discord.com/channels/684098359874814041/1006646242467659867/threads/1439816203353985055