Some refactorings on C++ code, many methods of the CApi class were moved to the App class, so the CApi now has only the Lua functions of the vega.capi table.
#16 Some changes on mainloop table, now it is started by the C++ app. The user script only needs to set the initial module using vega.mainloop.context.module = mymodule.
#16 Changed the context table to deny changes on scene and module fields while the frame is being updated.
#16 Added a simple test to mainloop.
#16 Fixed the usage of the scene and nextscene fields of the context.