Add text I/O for Kripke structures.

* src/kripke/kripkeexplicit.cc, src/kripke/kripkeexplicit.hh,
src/kripke/kripkeprint.cc, src/kripke/kripkeprint.hh: New files.
* src/kripke/Makefile.am: Add them.
* src/kripkeparse/fmterror.cc, src/kripkeparse/kripkeparse.yy,
src/kripkeparse/kripkescan.ll, src/kripkeparse/parsedecl.hh,
src/kripkeparse/public.hh, src/kripkeparse/scankripke.ll: New
files.
* src/kripkeparse/Makefile.am: Add them.
* src/kripketest/bad_parsing.test, src/kripketest/defs.in,
src/kripketest/kripke.test, src/kripketest/origin,
src/kripketest/parse_print_test.cc: New files.
* src/kripketest/Makefile.am: Add them.
* src/Makefile.am (SUBDIRS): Add kripkeparse and kripketest.
* README: Document src/kripketest/ and src/kripkeparse/.
* configure.ac: Generate src/kripkeparse/Makefile,
src/kripketest/Makefile, src/kripketest/defs.
* iface/dve2/defs.in (run2): New function.
* iface/dve2/dve2check.cc (syntax, main): Add option -gK.
* iface/dve2/kripke.test: New file.
* iface/dve2/Makefile.am (TESTS): Add kripke.test.

src/kripketest/origin

@@ -0,0 +1,4 @@
+state1, "!b", state2;
+state2, "a&b", state3;
+state3, "a", state4 state1;
+state4, "b", state1;