Draft: Proposal for CA-Based AODFix

The change-set here implements the proposal of AODFix with MT & ComponentAccumulator. See also the talk at the Reconstruction meeting. Reconstruction/RecJobTransforms/python/AODFixConfig.py contains the AOD-Fix infrastructure, to be added to AOD-reading jobs

The remaining files are part of a demonstrator that does nothing useful, not sure if they should really go in the repository.

ping @jcatmore