suzerain: rename slowgrowth{_type,}.hpp

git-svn-id: https://svn.ices.utexas.edu/repos/pecos/suzerain/trunk@45075 0bd85f0b-c151-43b9-a1e9-27231104551f
suzerain: remove linearize_type.hpp

Was fairly heavyweight for what it provided, it always required
operator_common_block.hpp anyhow, and slowgrowth_type.hpp just disappeared in
anticipation of work for #3089.

git-svn-id: https://svn.ices.utexas.edu/repos/pecos/suzerain/trunk@45076 0bd85f0b-c151-43b9-a1e9-27231104551f
suzerain: #3089 make slowgrowth a class

In anticipation of loading this down with some durable state,
convert the former namespace into a class.

git-svn-id: https://svn.ices.utexas.edu/repos/pecos/suzerain/trunk@45077 0bd85f0b-c151-43b9-a1e9-27231104551f
suzerain: stub slowgrowth.cpp

git-svn-id: https://svn.ices.utexas.edu/repos/pecos/suzerain/trunk@45078 0bd85f0b-c151-43b9-a1e9-27231104551f