Made the rapid syringe gun a subtype of the syringe gun, and reduced it's
capacity to four syringes.
Fixed the examine bug on syringe guns.
Added a new sprite for the regular syringe gun.
Added a new door for research. It's also used in robotics.
Updated the air injector sprite.
Fixed some pepperspray spelling errors.
~~REMOVED~~: the energy crossbow and chemsprayer from R&D.