Set up project files for the MonoDevelop LuaBinding

http://addins.monodevelop.com/Project/Index/98 is a nice help because of syntax highlighting, code completion and having one IDE to edit the whole project including missions.

![monodevelop-luabinding](https://f.cloud.github.com/assets/756669/1949236/8285a030-80f3-11e3-9449-bd699e37fb94.png)

Note: this requires a .lua filename policy change as having multiple "mission.lua" is not helpful in a project tree.