Fixing following problems:
Issue number one:
Enable mod with a23 compatibility in a23b.
Mod will be enabled and invisible in mod selection screen producing various errors.
Game will crash and refuse to start.
Show splachscreen with information about invalid mods in config on startup.
Issue number two:
Mods can silently set loaded mods without restarting the engine, so mods can unlist themselves from compatibility detection.
Display in enabled mods really enabled mods as current logic confuses players about which mods they have enabled and is not helpful (ref #4881)
this will not solve issue with mods claiming being compatible with engine version while in fact being incompatible.