* module/rnrs/6/exceptions.scm: Remove dependency on (rnrs syntax-case);
rewrite guard and guard0 in using syntax-rules in terms of syntax-case.
* module/rnrs/6/syntax-case.scm: Add syntax-violation implementation.
along with its dependencies.
* module/Makefile.am: Add new R6RS libraries below to RNRS_SOURCES.
* module/rnrs/6/conditions.scm, exceptions.scm, syntax-case.scm: New files.
* module/rnrs/io/6/simple.scm: New file.
* module/rnrs/records/6/procedural.scm, syntactic.scm: New files.
* test-suite/Makefile.am: Add tests/r6rs-records-procedural.test to SCM_TESTS.
* test-suite/tests/r6rs-records-procedural.test: New file.
