Belted-layer related balance changes

Prevent the tool belt from being fitted. Currently the tool belt is objectively better than the tactical dump pouch, because it can be fitted and specialized military equipment can't.

Allow the tactical dump pouch and the fanny pack to be fitted.

Remove the chest rig from the belted layer. It's a vest, and is not anything like a belt.

Move the purse to the belted layer. It's a purse, and is not anything like a shirt.

Remove the holster from the belted layer. It doesn't cover anything, so having it be belted doesn't do anything.

Halve messenger bag and runner pack volume to 10 and 9, respectively. They're still better than every single other 0-enc, non-fittable item on the belted layer. 

Allow the scabbard to be fitted. There's currently no reason to use a scabbard, which offers up to the equivalent of 17 volume (when sheathing a nodachi), when you can use a messenger bag, which offers 20 volume and is easier to find. Even after the messenger bag's volume is halved, messenger bags are still the better choice for carrying most swords without this change; only the zweihander and the nodachi are larger than 10 volume.

Allow both large and small quivers to be fitted for the same reasons.

Prevent survivor-brand backpack and rucksacks from being fitted, increase the volume to match their non-survivor-brand counterparts.