Improves core.debug
Improves core.debug

  - Adds format_exception(), that prints an exception with its type,
    which a simple str() might leave out.
  - The old 'details' string parameter to debug, log, warning, critical
    is now a variable number of strings or exceptions; exceptions will be
    formatted correctly (without traceback).
  - Fixes warnings.

hjanime/VisTrails,celiafish/VisTrails,Nikea/VisTrails,VisTrails/VisTrails,minesense/VisTrails,Nikea/VisTrails,Nikea/VisTrails,hjanime/VisTrails,VisTrails/VisTrails,minesense/VisTrails,minesense/VisTrails,celiafish/VisTrails,celiafish/VisTrails,VisTrails/VisTrails,minesense/VisTrails,hjanime/VisTrails,Nikea/VisTrails,VisTrails/VisTrails,hjanime/VisTrails,VisTrails/VisTrails,minesense/VisTrails,celiafish/VisTrails,hjanime/VisTrails