Add support for multiple game version instalations

[ak86]

Hello,
i have 3 skyrim versions installed for mod developement LE/SE/AE,
i would like extension to support multiple skyrim instalations instead of hardcoded LE and SE/AE:
LE - v?
SE - 1.5.97
SE (gog?) - 1.6.659
SE/AE 1.6.1130+