+ - Forest: keep() and valid() -- can we do this with states
+ rather than subtrees?
+
+ - hash Long->long: it's all bogus
+
+ * huge performance improvement (try for more)
+ * pick back up cleaning up end of Parser.java (Reduction)
+ * some weird edge cases; check last regression test, 'make doc'
+
+
+ - Sensible tree-printout
+ - make Tib.Block extend Tree<>
+
+ - more natural phrasing of metagrammar?
+
+ - finalize metagrammar and rdp-op's