Changes to ease code compilation in GCC.
Disk_t and HDD contain a std::string and for this reason they need a proper constructor, ZeroMemory is not guaranteed to work.
. Debug 'G(o)' cmd now defaults to normal speed (and precise video updates)
. New debug 'GG' cmd enables full speed (and periodic video updates)
. Single-stepping (normal or full speed) now routed through ContinueExecution()
. Removed Cpu6502()/Cpu65C02() check for debug breakpoints
. Removed the (undocumented) SHIFT+F7 feature to exit debugger for 'normal speed breakpoints'
. Removed the g_bDebugNormalSpeedBreakpoints variable