Makefile: Add generation of Vala documentation
DiskController: Improve documentation
Core: Improve documentation
Device: Improve documentation
Keyboard: Improve documentation
GameType: Improve documentation
Video: Improve documentation
Region: Improve documentation
Performance: Improve documentation
Memory: Improve documentation
Retro: Improve documentation
Module: Improve documentation
SystemInfo: Improve documentation
GameInfo: Improve documentation
Variables: Improve documentation
AvInfo: Improve documentation
Input: Improve documentation
Audio: Improve documentation
Makefile: Correct the version number