Needful things (simple additions to improve the game)

[KA101]

@RAM

It feels sort of irritating to have all these mod-slots on our guns and no mods to use with them. A bunch of craftable gun mods would be really satisfying, even if they they were over-specialised or inefficient and made the overall gun performance inferior in most respects.

Craftable mods would be fairly limited–bipods, grips, etc. This came up elsewhere and hit the no-precision-machining ban in the design doc.