New version of the miner for my pool

Some of you requested changes, i made them! New build 3 of the miner available at the same place: http://girino.org/metisminer/

New on this version:
1- option -d now supports more than one device (old syntax, -d 0,1,2,3 etc)
2- option -I for "gpu intensity" (same as -s on ypool miner, but -s was taken by some networking options). USE WITH CARE, values too high might freeze the program, values too low will be rejected by the GPU. Default is "-I 19". I don't recommend values above 25 or bellow 15.

I still have to implement an efficient CPU miner. The default implementation (that comes wth the wallet) is even slower than using opencl on the CPU device. So for those looking for CPU mining, i'll work on it for next week.

Thanks to all for the support, and happy mining.