Moved the BT48x hardware cursor draw function to the RAMDAC's code where it belongs;
Renamed the BT48x RAMDAC code file to vid_bt48x_ramdac.c (was vid_bt485_ramdac.c);
Fixed BT48x 64x64 hardware cursor bugs (caused by the index variable being uint8_t when it should have been uint16_t) introduced in the previous commit.
