Changes from 1.4:

- added hestParseOrDie(), which basically encapsulates the way
that everything else in teem uses hest: if they didn't give you
command-line args, or the args can't be parsed, then complain
and exit(1).
- added hestElideSingleEmptyStringDefault and the associated
member of the hparm struct, elideSingleEmptyStringDefault.
With this true, if parsing a single string, and the default
is "", then the default will not be displayed in the glossary.

from 1.5beta0:
- added hestCleverPluralizeOtherY, which is smartness on how
to pluralize callback objects, when their name ends with Y