Make workflow pickleable
 Cosmetic changes
Merge remote-tracking branch 'mpmaster/master'
 Save UnitError as class attribute of Unit, FloatWithUnit, ArrayWithUnit
 Refactoring task.status
 Preparing refactoring of EventParser
Merge remote-tracking branch 'mpmaster/master'
 New method to recheck the status of the tasks
Merge remote-tracking branch 'mpmaster/master'
 Better treatment of possible errors raised by ABINIT
Merge remote-tracking branch 'mpmaster/master'
 Minor changes in abinitio objects.
Merge remote-tracking branch 'mpmaster/master'
 Modified HighSymmKpath: use true division everywhere in the module + dump UserWarnings
 if the lattice_type and/or the spacegroup_symbol returned by spglib do not have the expected format.
Merge branch 'master' of github.com:materialsproject/pymatgen