first idea of GHistWriteList. All Histograms will be added to Lists corresponding to the Folders.
This list will be written sequencly, all Folders will be completely filled in one write.
changed pi0-example for testing. GH1 contains now only GScaCor.
Added Calc Result, to seperate summing histograms and writing. Also several bugfixes in GHistScaCor.
Revert "changed pi0-example for testing. GH1 contains now only GScaCor."

This reverts commit 5b04eee38c6af131a58a857ef85ed85f91a44d07.
small bugfixes in GHistTaggerBinning.
Added CalcResult to GHistGBSub. Several changes to get GHistBGSub working. Problems with TaggerBinning in GHistBGSub.
TaggerBinning is OK in Prompt and Rand windows, but empty in RandSum and result.