x[n] algorithm .cl-file optimizations

After extensive testing a couple of us in the bitcointalkforum, @badman74, @bullus77 have found these particular settings to be highly optimal and stable as long as you do not shoot for the moon with your overclocks.  This should alleviate hashrate loss and allow for the closing of https://github.com/sgminer-dev/sgminer/issues/347, https://github.com/sgminer-dev/sgminer/issues/357, & https://github.com/sgminer-dev/sgminer/issues/358
Getting kind of tired of manually editing the .cl files for every nightly build, so let's push this to develop first, with the ultimate intent of getting them into v5_0 as fast as possible.

Thanks!