Mammoth Tank buff; balance stick for MLRS

Mammoth tank buffed, since people said it was too slow and died easily, e.g. dying too readily while approaching enemy through artillery fire.
-HP increased from 600 to 800. Seems justifiable since it's an expensive, slow-to-build, top-tier unit.
-Speed increased from 3 to 4; (C&C 95 default value, incidentally)
-Rotation reduced from 5 to 3 so that it has a flavor of slowness, and a vulnerability.

MLRS speed reduced from 8 to 7, so it's not uncatchable when retreating.
MLRS health reduced from 120 to 115 so Rocket Bike can kill it in 5 shots instead of 6.
MLRS InitialStance set to Defend, to help noobs avoid unintentionally bunching them up (and making them vulnerable to airstrikes, etc.) and to require less micro-management of their positions.