Mecha fixes.

[MistakeNot4892]

Fixes most of the now-removed lines from #508.

• Adds better qdel() assurance to mechs.
• Removed unused mech gear.
• Adjusts a bunch of minor checks and var passing that resulted in nonfunctional mech behavior.
• Adjusts default cell, cell drain rate, and cell power cost for RCDs.
• Fixes mech equipment being nonfunctional.
• Adjusts/tweaks mech construction and deconstruction. Hardpoint equipment now survives the mech despawning.
• Hardpoint items now follow the holder's move event for the purposes of light updates.