suzerain: remove virtual destructor

git-svn-id: https://svn.ices.utexas.edu/repos/pecos/suzerain/trunk@45105 0bd85f0b-c151-43b9-a1e9-27231104551f
suzerain: #3089 use new-ish perfect::slowgrowth

Replaces a bunch of messy, inline logic with calls
to member methods for a messy, stateful object.

Advantage being, however, that one can read them
in isolation and the object can be reused multiple
places.

apps/perfect/manual.gold solutions all continue to pass
after this change, at least on GCC --enable-debug builds.

git-svn-id: https://svn.ices.utexas.edu/repos/pecos/suzerain/trunk@45106 0bd85f0b-c151-43b9-a1e9-27231104551f