suzerain: #2736 quantities towards libsuzerain

Begins to move much of the quantities logic into the libsuzerain
under the name suzerain::samples, SUZERAIN_SAMPLES, etc.

git-svn-id: https://svn.ices.utexas.edu/repos/pecos/suzerain/trunk@43637 0bd85f0b-c151-43b9-a1e9-27231104551f
suzerain: reduce header coupling

Forward declarations are just fine here.

git-svn-id: https://svn.ices.utexas.edu/repos/pecos/suzerain/trunk@43638 0bd85f0b-c151-43b9-a1e9-27231104551f
suzerain: #2736 {save,load}_samples

Logic stolen from apps/perfect/quantities.{c,h}pp

git-svn-id: https://svn.ices.utexas.edu/repos/pecos/suzerain/trunk@43639 0bd85f0b-c151-43b9-a1e9-27231104551f