Merge pull request #1 from vadler/master

master - Start up.
Merge pull request #2 from vadler/master

b-Tagging
Merge pull request #3 from vadler/master

Factors
Merge pull request #4 from vadler/master

Histograms
Merge pull request #5 from vadler/master

Fix empty histograms.
Merge pull request #6 from vadler/master

Loops
Merge pull request #7 from vadler/master

Diff filling
Merge branch 'master' of github.com:cms-analysis-tools/L2