core: add functions to manage array lists
core: add extra check on arraylist pointer in arraylist functions
core: reset data contents in function arraylist_clear if size_alloc_min > 0
core: add comment about argument "index" of function arraylist_search
tests: add tests of arraylist functions
core: optimize completion by using arraylists

With arraylist (vs weelist), the completion is about 50x faster.
It is visible on "/help [+tab]".
core: use a sorted arraylist for partial completions

With a sorted list, the partial completion is about 50x faster
(like other completions).
Merge branch 'arraylist'
doc: add file "wee-arraylist.c" in developer's guide
doc: update auto-generated files with hdata