Preliminary support for Optic (quick-and-dirty but it seems to work)
 Easier API for the definition of OptictTasks
 Polymorphic interface for OpticsTask that accepts FileNode objects
 Add new script cif2spg.py
 Add script for the computation of the deltafactor.
 Remove support for Workflows in abirun.py
 Add doc to run_deltafactor.py
 Minor changes.