move version-specific code to CGameVersionManager

[x87]

          please move it to CGameVersionManager, it's better to keep all hooks in one place for future support of more versions/games.

can be done in a follow-up PR

Originally posted by @x87 in #197 (comment)

[MiranDMC]

CGameVersionManager should be rewritten to use text identifiers instead enum. Then CLEO export can be added so other plugins can benefit from it too. It would also make possible to display meaningful error messages about some function not being supported in current game version.