Add support for radare2

[XVilka]

radare2 has it's own IL - ESIL, but it can be converted into REIL, using 'aetr' command. Or there is another option - to reuse radecoIL from radeco-lib.

[montyly]

That sounds cool, I will re-write the importation functions of GUEB in the near future, so I will take a look.
Thanks for the information.