Finish cleaning up command-line options. See #144.

Replace -boot_no_smb_in_temp with a new option
-boot_temperature_heurictic {smb, quartic_guess}.

Fix the "-gradient" option (used to accept "new" and then fail.)

Improve the "-test_climate_models" option (turn off more things).

Add code checking for old options removed while working on #144 and
stopping PISM with a somewhat helpful message.