General:
- changed checking for SHA-1 hash - now the iNES header is not included in hashing a file;
- misc code cleanup and refactoring.

Board:
- added mapper 46;
- added mapper 60;
- added mapper 76 (Namco-3446);
- added mapper 93 (Sunsoft-2 on a Sunsoft-3R board);
- added mapper 169;
- added mapper 180 (HVC-UNROM+74HC08);
- added mapper 240;
- added mapper 246.