add save file validation

[bigfarts]

• ensure opposite version gigas are not allowed
• ensure exe6 chips (hakushaku, gdsex, falzar, gregar, dblbeast, django, otenko) are not allowed on bn6 games
• navicust+kaizou legality checking
• check linknavis
• apparently you can set normal shot/chargeshot to something weird? need to make sure this is not set