Introducing Elua: an EFL-LuaJIT app runtime

This set of changes introduces an initial version of Elua, which aims to be an easy to use
application runtime for the EFL. It's built around LuaJIT for maximum performance and
includes Lualian, an Eolian based binding generator.

Elua is currently in very early version and not everything works (particularly, binding
generation is not finalized). It's, however, ready enough to get some feedback.

Merges branch 'devs/q66/lualian2'.

@feature