This fixes an off-by-one bug in the atom type validation check. Closes#91.
It also enables type and style hints by default and replaces
the -charmm command line flag with -nohints flag (to turn them off).
Hints are also added to section headers.
Add a brief minimization to example input template.
Step patch level version to 1.8.3.
CGenFF/Charmm-GUI generated parameter files and other recent CHARMM parameter files seem to be using the marker IMPROPERS instead of IMPROPER. with this change, both are recognized and translated to the same number (4).