* start using boost:stacktrace in invariants
* make this linux only
add RDK_USE_BOOST_STACKTRACE config variable, just in case (it's not actually needed now)
* Deprecation: planned removal of .message() and .getMessage() methods
* Deprecation: planned removal of old MolHash code
* document deprecations
* output the diffs when the psql tests fail
* remove .message() from SWIG wrappers
note that the KeyError doesn't work properly. We should clean up the the exceptions here anyway
* typo