v0.9.3.4 RC

Fixes:

- lowered time_safe in xr_combat_ignore.ltx to 30 secs

- finalized sway effector settings

- made 'NR 40' knife usable

- made UPD unloadable

- made GSH-18 use 9x18 ammo as it should

- made repair UI again display material bonuses ammounts properly

Gameplay / balance:

- implemented 'Concealed IEDs' from ponney (it also makes IEDs
functioning as mines)

- re-balanced economy somewhat towards making it more harsh:

* lowered 'junk items' prices by 30-50%
* lowered artifacts prices by 30-50%
* increase mechanic repairs costs by 40%

- made NPCs slightly less resistant to headshots