arcing projectiles

curvature should start at (1.73 / sqrt(sqrt(70.0 / 10.0)) = 1.06358350461)
rather than 0.5 for arcing shots, as strength and weight are assumed to be
70 and 10 respectively
smoke inhalation by ruleset
haha derp
fix up occasional weird error message with TU reserve
rethink: tie error message to setting

the underlying logic can stay the same, but the error message should
probably be consistent with the player's reservation setting.
fix copypasta
Fix RMPs being limited to 127 instead of 255.
fix up TFTD bullet sprites

top four rows were reference material.
fix fix
add missing stat