Vastly improve the sound for the Cave PGM games

[arcadez2003]

This also improves the sound more generally for all the other PGM games.

we're keeping the original timers from MAME106 rather the adjusted ones from shmupmame otherwise the games take a big hit in performance .

Big thanks to the shumpmame project for the code

[arcadez2003]

@amadvance I noticed you added support for the Cave pgm shmups some years back, i dunno if you were aware
that the shmupmame dev also added these games and for good measure vastly improved the music sfx and speech
for them via the soundcore.??

Eitherway i've finally got around to adding these changes here allbeit without his tweaks to the ICS2115 timing as
i found that impacted hugely on the performance of these games, luckly the games now sound lovely and we
keep the framerate nice and high via the older timer code it's a double win basically.

Consider this an early xmas present and your welcome :)

[amadvance]

Thanks @arcadez2003
I'll lookup at shmupmame if I ever get time :)