Program generalise

[DWalker487]

Updates to the program interface, to give some default definitions and remove some redundant functions that are not necessary for Backend objects (in theory they are internal helper methods for program objects). As a result it is no longer a pure interface, but probably more helpful for users, i.e. Marian.

Also included are updates to:

• programruncard to use full modules2 runcard parsing,
• nnlorun.py to include the possibility of using cvmfs lhapdf rather than an initialised one

[DWalker487]

I think this has been tested and we're reasonably sure it works at this point, so I'll merge in.