Fixed small bugs in USGS CenCalVM queries.

Switch to maxres queries. Decrease elev until Vs > 0. Fix trapping errors. Don't query below max depth of model. Use minVs.
Add output of USGS model label in log file.
Enable FCFLAGS to allow user to customize Fortran flags (debugging) via configure.
Merge branch 'baagaard/enable-fcflags' into baagaard/master

* baagaard/enable-fcflags:
  Enable FCFLAGS to allow user to customize Fortran flags (debugging) via configure.
Merge branch 'baagaard/master-add-model-usgscencalvm' into baagaard/master

* baagaard/master-add-model-usgscencalvm:
  Add output of USGS model label in log file.
  Fixed small bugs in USGS CenCalVM queries.