suzerain: S_RT signal from 75 to 120 seconds

I've seen at least one production run where I couldn't get the data
to disk fast enough.  Increase the amount of time before shut down that
we consider for dumping to disk.


git-svn-id: https://svn.ices.utexas.edu/repos/pecos/suzerain/trunk@45328 0bd85f0b-c151-43b9-a1e9-27231104551f
suzerain: bump shutdown horizon

git-svn-id: https://svn.ices.utexas.edu/repos/pecos/suzerain/trunk@45329 0bd85f0b-c151-43b9-a1e9-27231104551f
suzerain: simplify sorted(...) workaround

http://stackoverflow.com/questions/24093363/


git-svn-id: https://svn.ices.utexas.edu/repos/pecos/suzerain/trunk@45330 0bd85f0b-c151-43b9-a1e9-27231104551f
suzerain: add natural(...)

sorted(foo) breaks for the same reason canonical was introduced.
Rather than leaking the fix for unit tests, add natural(...).


git-svn-id: https://svn.ices.utexas.edu/repos/pecos/suzerain/trunk@45331 0bd85f0b-c151-43b9-a1e9-27231104551f
suzerain: use LooseVersion

To pass './propagation chk' atop SymPy 0.7.4.1 I needed LooseVersion
and not StrictVersion.


git-svn-id: https://svn.ices.utexas.edu/repos/pecos/suzerain/trunk@45332 0bd85f0b-c151-43b9-a1e9-27231104551f
suzerain: use natural for SymPy 0.7.4.1 compat


git-svn-id: https://svn.ices.utexas.edu/repos/pecos/suzerain/trunk@45333 0bd85f0b-c151-43b9-a1e9-27231104551f