Various fixes and balancing

--Cannon and short-barrel cannon models are now skinnier
--CoH sounds fixed
--Small v12 petrol/diesel and medium v8 diesel weight slightly increased
--Large CVT torque rating increased from 3400 to 6000
--37mm cannon name fixed
--37mm short-barrel cannon rof adjusted
Some new tank sounds

Engine and a few misc
Resampled new sounds to 44100 hz
Merge remote-tracking branch 'upstream/master'