berry: validation step print
berry: print validation fail point while valid_cmd
berry: print validation fail reason of valid_cmd
debug densifier

the first error found by the validator
modify tester
removed is_rec from update_mode
Merge branch 'master' of github.com:skcho/zooberry

Conflicts:
	analyzer/pre/itvPre.ml
	analyzer/semantics/itvSem.ml