Remove mention of the removed syntax extensions from the META file
BatList: fix BatList.n_cartesian_product [] = assert false

`BatList.n_cartesian_product [] = assert false` is clearly a bug.
Add a case `[] -> [[]]` because [[]] seems to be one right answer mathematically.
Remove the case `[l] -> List.map (fun i -> [i]) l` because it becomes unnecessary.

Add unit tests for n_cartesian_product.
Merge pull request #360 from wistery-k/fix-n_cartesian_product

BatList: fix assert failure on `BatList.n_cartesian_product []`
Clean up some pa_llist remanents

A little bit of pa_llist was found in myocamlbuild and testsuite/_tags
Fix #363: generalize Set.map's type, add op_map

op_map covers the special case that the mapping function is order preserving and the tree doesn't need to be rebuilt.  Otherwise map rebuilds the whole tree
BatText: remove deprecated Invalid_rope exception
Merge pull request #365 from kerneis/remove-invalid-rope

BatText: remove deprecated Invalid_rope exception