Creating extended pdf, nll, and everything else in the loop.

Sorted out sigpipe problem with parallel threads by going single-thread
Fixes to diphoton selection.

Details
- uninitialized diphoton indexes
- re-initialization of mva values when evaluating systematics
Merge pull request #173 from adavidzh/fix_bands

Fixed bands
Merge pull request #179 from musella/fix_dipho_selection

Fixes to diphoton selection.