More correct code
More correct code

Lots of parameters were directly accessed without being declared as
required or providing a default value. That is incorrect, however the
problem does not show up as long as the clients provide the right set of
values.

Refs idaholab/relap-7#19688
jessecarterMOOSE/moose,sapitts/moose,bwspenc/moose,harterj/moose,dschwen/moose,idaholab/moose,bwspenc/moose,andrsd/moose,milljm/moose,idaholab/moose,dschwen/moose,idaholab/moose,idaholab/moose,andrsd/moose,laagesen/moose,jessecarterMOOSE/moose,andrsd/moose,dschwen/moose,lindsayad/moose,lindsayad/moose,lindsayad/moose,jessecarterMOOSE/moose,bwspenc/moose,lindsayad/moose,milljm/moose,jessecarterMOOSE/moose,sapitts/moose,jessecarterMOOSE/moose,laagesen/moose,harterj/moose,sapitts/moose,sapitts/moose,andrsd/moose,milljm/moose,dschwen/moose,milljm/moose,harterj/moose,laagesen/moose,lindsayad/moose,sapitts/moose,milljm/moose,idaholab/moose,bwspenc/moose,laagesen/moose,dschwen/moose,harterj/moose,bwspenc/moose,harterj/moose,laagesen/moose,andrsd/moose