fix doc
updated readme
Merge branch 'dev'
bugfix in cnf
merge from dev: bugfix in cnf
minor improvements
hooks for CNF
cli flag to disable ordering generation in hysteresis
more abtract requirement for Clause index (feature vector...)
Merge branch 'dev', with bugfixes and API change for Index.ClauseIndex
a few more functions on Multiset and Formulas
module lib/IArray  for immutable arrays;
used in Multiset
background stuff:
- lexicographic combinators in Comparison;
- small changes to Cache and Hash;
- list comparison/max element in Multiset
more tests
Merge branch 'dev'
another combinators for comparisons
in NPDTree, do not capture Not_found that could be raised by the
user callback
redundant cli option
Unif: equality up to substitution implemented
printer hooks in formulas