Robust squash

Squashed version of #5360

Baton rework:
Batons now operate off of power cells. Power cells can be removed with a screwdriver. Each baton has 10 hits worth of charge with the starting cell. The cost is 1000 units of power for both the cell and cyborg cells, though this is easily tweaked down if it cripples secborgs too much in practice.

Improvised weapons:
-Switchblade (Metal + Plasteel)
-Bats (Wooden and metal, fashionable from stacks)
-Spear (Made from metal rods + cablecuffs + glass shard, dangerous.)
-Stunprod, improvised stun baton, made using a rod, cablecuffs, wirecutters, and a power cell. Less-stealthy alternative to stungloves. (We can remove or nerf them now, perhaps.)

Balance tweaking:
Increased time on the weaken from punches and the knock-down on weapon blows. Mildly decreased push time to shift push away from becoming the be-all end-all of single combat again, especially in unarmed situations.

Embed tweaking:
Made embedding much more likely to proc on melee. It was nigh impossible with anything but an e-sword, an axe, or admin-spawned weapons in the past. There is now a minute chance for many more thrown and swung weapons to proc embedding on a hit, and much more likelihood for them to cause significant damage on removal. This was done to increase the lethality of a melee with sharp or not-so-sharp-but-sufficiently-motivated objects.