Merge branch 'master' of https://github.com/mamedev/mame
Add compile-time option to show visible annoying red border when sound is overdriven. Leaving it on for a bit at the start of the cycle so that devs might identify and fix some of these cases.
Fix overdriven sound in various Atari games.
mario: Reduce volume so we don't clip constantly just when running around.
MT2099: Reduce overdriven audio volumes.
gaelco3d: Fix overdriven sound
toaplan2: Fix ridiculously overdriven sound
dec0: Fix overdriven sound