Update 3. Repair mechs and special weapon bufs

Added a new weapon customization menu.
Added modification of critical hits
Added modification of slowing hits
Added modification to create fire zones
Added shotgun modification
Added modification of explosive shells
Added modification of penetrating shells
Added slowdown state for bugs

Added mech repair menu
Added special mech damage

Optimized save code
Optimized shell creation code
Fixed an issue with the display of the rammer beetle
Fixed negative speed value