Enhancements:
Added REU support (Sonic, Vision Basic) (#735).
Added VSYNC support (#747).
Emulation speed can be adjusted continuously (slow motion / time lapse) (#751).
Audio buffer fill level can be displayed in the status bar (#750).
Added a fifth drop zone for flashing programs into memory (#748).
RetroShell has gotten a special debug mode (#746).
Both Command keys can be mapped to C64 keys individually (#737).
Coding:
Ported the event scheduler from vAmiga ( #749).
