Precalibration config files and NVRAM for Light Gun games (WIP)

Set of config and NVRAM files precalibrated for gun games using compatible Light Gun (with some game exceptions like adsticks used by Terminator 2 : The Arcade Game). Those files are generated when launching game for the first time; if it exists already, Batocera will ignore it. All settings within are set to defaults, only the gun calibration was made true Plug-ang-Play experience with maximum accuracy.

Specific tweaking for games and updates will be made over time.

Current calibration done :

1. Atomiswave
2. NAOMI
3. Model2
4. Model3
5. MAME (standalone, lr-mame2003plus, lr-mame*).
6. Wii
7. Namco 246/256

Calibration to do :

1. Arcade (libretro-FBNeo)
2. Sega Saturn
3. Dreamcast
4. PSX
5. 3DO

If a calibration or tweak is missing, feel free to do it yourself and make a pull request.

*Must place files from /saves/mame/ (MAME standalone) to /saves/mame/mame (lr-MAME)