Added a region_width variable to change the amount of background fit
Finds the area of the gaussian peak
Separated the step function from the photpeak in auto_eff
Integrates skewed gaussian properly in auto_eff
Proper covariant errors in fit results in atuo_eff
Re-added readme (mysteriously vanished)
Merge pull request #18 from r3dunlop/master

Upgrades to auto_eff