- this implements blargg's nes ntsc filters using core options
- an optional height doubling is also added but disabled for performance reasons (might make that optional as a core option)
- since PS2 and PSP have their own blitter branches, these platforms do not have the ntsc filters since i dont have the means to test on those systems.
- compile with HAVE_NTSC=1 to have these options, HAVE_NTSC=0 disabled filter including core options
- HAVE_NTSC=1 is set as default, other than PS2 and PSP as stated above.
