version 8.4

• added a few new library functions: string.endswith(), diskio.send_command(), diskio.diskname()
• improved error checking in diskio.directory()
• fixed rounding errors in signed divide by power-of-two
• on C64, the cx16.r0...cx16.r15 virtual registers are now moved into zeropage if possible.
• allow bool return type (and arguments) for asmsub / romsub
• removed several problematic code optimizations (may lead to larger code size unfortunately)
• added a few new code optimizations related to mkword() and logical expressions
• several bugfixes and improvements.