Multiple BMC64 enhancements

[rhester72]

Includes:

• Allowing empty tape image creation from within the BMUI
• Allows selection and creation of G71 disk images (already part of underlying VICE 3.3) [see https://sourceforge.net/p/vice-emu/bugs/1564/]
• Improved PET sound from upstream VICE [see https://sourceforge.net/p/vice-emu/bugs/1430/]
• Inclusion of full VICE 3.3 palette selection to all emulators
• Improvements to real machine video timing for all machines over custom HDMI (via machines.txt)