ecore - efl threads - add thredio class

ecore - efl threads - add thredio class

this adds a simple indata and outdata void ptr to begin that you can
set on efl.thread objects (set the indata) and get the outdata too to
get results. then on the efl.appthread side the indata is set on the
efl.appthread before it runs and on quit the thresad can set the
outdata on the appthread, and this appears back on the efl.thread
object in the parent thread.

so you can basically share pointers to anything in and out this way on
start/exit in addition to string args etc.

the reason i made it an extra class (mixin actually) is for future
expansion. sharing more complex data - eina values maybe or objects as
long as they are shared objects, and perhaps acting as an interface
for calling a function at the other end like ecore_thread_async_call
etc.