Removed old alternative emissions API
In ObjectCollection, fpre and fpost now replace the old callbacks
fpre functions must return True or False to add/remove an object to/from the collection
extensions property of 'Emission' is now independent of base emission fields.
added 'get_all' method for ObjectCollection
now base emission field objects are assigned to extension objects rather than the opposite
added tree views (networkx, matplotlib, d3.js) in examples
Update to new version of configuration file:
- now allow settings with extensions
update
Merge branch 'iextensions' of /Users/Christoph/git/pyHEMCO into localmerge
Update to iextension
- io routines updated to new extension objects type