Dehardcode Lua API_REVISION
Currently Lua API version is hardcoded here.
It would be good to show the version in documentation and in OpenMW main menu (under "revision" in bottom right corner). Otherwise users may be confused if they use OpenMW build and documentation from different revisions and some Lua commands don't work.
The number shouldn't be duplicated in 3 different places. We can specify it in CMakeLists.txt the same as OPENMW_VERSION and then reuse in other places (see 1, 2, 3).
Edited by Petr Mikheev