Having version.hpp throw an exception when built against a malformed
version number (due to, eg, not having the git tag available in an
automated package build from source bundle) results in _init_ failing
during an otherwise apparently successful dlopen(), as well as the
netgen-mesher executable crashing before hitting main().
This patch both forces an abort and prints a helpful message alerting
the builder/user that something went wrong instead of handing over
either a coredump or a weirdly malfunctioning library with no apparent
cause. Hopefully this will avoid a repeat of automated Fedora builds
shipping nonfunctional Netgen RPMs for several years!
