Added new experimental control for overall emulation speed. This
lets you specify how fast/slow the gameplay should happen relative to
the original. -speed 1.0 means run at normal speed. -speed 2.0 means
run at 2x speed. -speed 0.5 means run at half speed. Note that the
sound pitch is shifted as a result. If you are running early Namco
games that normally run at 60.60Hz, you can run them at -speed 0.99
and it should run at under 60Hz, which should prevent sound stuttering
if your monitor is not capable of greater than 60Hz refresh rates.
If this turns out to be useful, future versions may support a
-speed refresh parameter that automatically tweaks the speed to keep
you under your monitor´s refresh rate. [Aaron Giles]