Added a CLEANUP mechanism to the exception handling library. Fixed a bug in the way setjmp() return codes were being handled that lead to infinite loops in some cases, exceptions getting missed in others. Made FINALLY {} a required element (unfortunately).

demo/catchgroup.c

@@ -4,10 +4,12 @@ int main(void)
 {
   TRY {
     THROW(2, NULL);
+  } EXCEPT {
   } CATCH_GROUP(1) {
   } CATCH_GROUP(2) {
   } CATCH_GROUP(3) {
     EXCLIB_TRACE("Inside of CATCH_GROUP");
+  } FINALLY {
   } ETRY;
   return 0;
 }