Background properly being drawn to screen

- Fixed error in pixel drawing location in TinerasNES::drawScreen.  Was
doing [ppu.framePreBuffer[(i * 256)] instead of [ppu.framePreBuffer[(i *
256 * 4)].
- Changed setPPUByte to accept an unsigned char instead of signed.  This
was screwing up writes to 't' & 'intPPUAccess'
- Need to add reference instead of direct access for
TinerasNES::drawscreen rgbData
- Changed intPPUAccess to VRAMAddress