* module/rnrs/6/exceptions.scm: (guard0, guard): New syntax.
* module/rnrs/records/6/procedural.scm: (r6rs-raise-continuable): Can't
use `raise' here because it's exported by (rnrs exceptions); use plain
old `throw' instead.
* test-suite/Makefile.am: Add tests/r6rs-exceptions.test to SCM_TESTS.
* test-suite/tests/r6rs-exceptions.test: New file.
