make a jthermcalc_util.F to contain utility routines (used by jthermcal &
jthermcalc_e107). Also add the possibility (turned off by default) in the
interfast routine to do extra sanity checks.
turn chemthermos, euvheat, hrtherm, jthermcalc, jthermcalc_e107,
paramphoto_compact and photochemistry into modules.