Improve support for dijet hypos
This merge request includes a number of miscllaneous changes that include better comments, and improvements to debug tools.
The hardcoded scale factor in the dijet mass calculation has been removed. Flownetwork construction errors for dijets have been fixed. Have CombinationsHelperTool and PartitionsHelperTool discover there children's jet multiplicity requirements rather than hard-coding these in the the chain label.
Edited by Peter Sherwood