suzerain: #2463 default restart interval for BL

Adds a "freestream"-ish default restart interval for the boundary
layer which is independent of the wall-normal domain size.

git-svn-id: https://svn.ices.utexas.edu/repos/pecos/suzerain/trunk@44044 0bd85f0b-c151-43b9-a1e9-27231104551f