custom mame build

[ksherlock]

• [x] VGM support (won't be merged into standard mame)
• [x] only include apple2-related drivers. Use standard mame if you need more.
• [ ] Touch Bar reset key?
• [x] vmnet helper?
• [x] command-Q, etc to command-option-Q so command key can be used in the emulator?
• [x] adjust mame ini path handling?
• [x] do something about the mouse in window mode
• [ ] command line flags to set zip speed?
• [ ] apng support?
• [ ] fix aspect ratio of generated .png/.avi files?

[ksherlock]

-mouse flag captures the mouse. but it won't be released while mame is active. (aside from pausing). would be nice to have a key combo that disabled mouse capture.