Set install dir for emscripten
While not required, should help compatibility with older cmake versions.
fix
issue #8: Static skull and bones flakes near the water in Sudden Death in themes without flakes
fix for
issue #71: Lua API: “Theme” variable is set to empty string initially
Lua-API - GetClanColor: Verify argument and display error message on fail (instead of engine crash)
issue #94: Seduction text is outdated and misleading