Customise forward ParticleFlow linking

This customises the particle flow linking between the extended tracker and the HF.  It is to activate the work done in #3482.  See @bachtis' talk in the 24/Apr/2014 TP studies meeting.  That pull request also brings in a configuration error in step3 by referring to a file that is missing from the pull request.  To fix that I changed the default back to the original file.

This pull request might need some changes depending on the response from @bachtis.  Since this also fixes some tests I'll merge this and add any changes required in a subsequent pull request.