Example how to compute the efficiency-corrected yields + simplifications for optional fields

--> THIS BREAKS BACK-COMPATIBILITY!! See the description for more details. <--

Added an example how to compute the efficiency-corrected yields.

Added a script to compute the yields, taken from the Lb2LcD0K. Most of the code is for monitoring purposes, in principle I could remove that to make the code more transparent.

Update of the make2DEff and mean2DEff scripts. Some fields of the config files are renamed, to make them more consistent: this breaks back-compatibility.

Added their sections to the README, together with some tests.