- We just use shaders for scanline if needed. ntsc + height doubling causes performance hit
for some slow devices. Any decent platform should be able to handle scanline effect shaders at least.
- do overscan cropping after the ntsc frame is generated. this allows
removing left and right screen artifacts when using horizontal crop like
what you would see happen in TV when adjusting horizontal size (HSIZE).
- add core option that implements NTSC scanline effects. This requires
framebuffer to double the height, so a define is added (NTSC_SCANLINES at
the top of libretro.c) to disable this on some low-memory platforms or just disable NTSC filters altogether.
- some minor cleanups
- 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.
- This creates 2 new advance core options to minimize the number of core options shown
-- Advance System Options contains:
--- Overclock
--- RAM power on state
--- no-sprite limit
--- simultaneous opposing direction press
--- zapper crosshairs
-- Advance Sound Options contains:
--- Master volume
--- Sound quality
--- on/off for NES' 5-channel apu
- This also re-arranges the core options when advance options are shown, system options on top,
gfx/palette/geometry options next, input etc.
