AVL: Minor edit

There was a let that was uselessly rec
AVL: Change API not to carry around comparison functions
Merge pull request #3 from nbraud/avl

AVL: Change API (why not, it makes for a usable polymorphic map)
update readme
udpate the type of CCKlist
update the klist type in other modules
remove ugly tabs
safe version of fold_right
more functions for CCOpt
printing error in LazyGraph
more explicit type declaration
crazy input-driven parser combinators
updated test in parseReact; fixed a bug
CCList.filter
operations on arrays (filter, filter_map, flat_map)
CCBatch: batch operations on collections, with some fusion optimizations
to reduce the numbre of intermediate collections
updated CCBatch (more optimizations and type-safety,
enforcing some structural constraints with GADT)
expose the optimization to the user in CCBatch
more operations on collections;
optimization level as a parameter in CCBatch
benchmark for CCBatch on list, array, and klist