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.
Issue number two:
Mods can silently set loaded mods without restarting the engine, so mods can unlist themselves from compatibility detection.
Enable necessary mods instead if running with gui and open mod page.
Open information window on top of mod page to infom why mod page is showing up.
On mod page show mods which failed in compatibility check and color the resposnible ones.
Disable start button without enabled mods.
Show non existed mods if they failed in compatibility check.
Else just log to mainlog and close.
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.