* Currently has some timing issues.
* Added privileged memory access to the main PlipMemory class.
* Inaccessible memory now properly returns 0xFF in the DMG core.
* A bit simpler and less contrived; should more closely match how the
hardware actually works.
* Still has issues and needs a lot of work, but this should prove to be a
better foundation to work from.
* HALT is now properly aborted if an interrupt comes in, even if none are
enabled.
* The timer is now implemented somewhat closer to spec, though it's still
not quite right (i.e. failing test cases, yadda yadda).
* ADD SP, e: Corrected H/C flag behavior.
* LD HL, SP+e: Corrected H/C flag behavior.
* POP/PUSH: Now properly clears out the low nibble of the F register.
* Renamed some opcode execution functions to be more accurate.
* Now passes blargg's 01-special.gb and 03-op sp,hl.gb.
* BUG: Output of blargg's test isn't quite accurate (missing chars). Might
correct itself when compliance is improved.
* The LCD will now force a blank frame when disabled.
* Emulation of the SameBoy DMG boot ROM now looks correct, but the LCD
stays off if the screen is toggled in a single vblank period. Not sure
if this is correct.
* SET and RST opcodes were flipped. Whoops.
* The interrupt flag will now be affected even if the IME is disabled.
* SameBoy DMG boot ROM now boots successfully (albeit with graphical
bugs).
* Added a GetPc() function to the core.
* A breakpoint can now be set on the program counter.
* Added a command line parameter that starts emulation in a paused state.
* The DMG core's register dump function now dumps the state of the IME flag.
* Split the game loop out of main.cpp and into its own class.
* The console now takes a std::function instead of a C-style function
pointer. It can actually work with class instances now! :o
* Added a standardized way of dumping registers.
* Added pause, frame advance, and machine cycle stepping support.
* The console's 'M' glyph now looks better. This is the most important
change in this commit, by far.
* Added missing grave character to the console font (whoops).
* Moved string functions from Config to its own static class.
* Implemented console quit command.
