lib: new "header_holder_type" container option
lib: default option for header_holder_type
lib: extra template parameter to containers & makers, not used yet
lib: new utility structs
default_holder: default header node holder
get_header_holder_type: type function producing header_holder_type
lib: extra template parameter propagated to impl bases, not used yet
lib:
renamed struct: default_holder -> default_header_holder
renamed holder methods: get_header_node -> get_node
TTI checks not working
lib: core implementation of header_holder in list_impl
lib: removed some unused methods
lib: core implementation of header_holder in slist_impl
lib: removed some unused method bstbase3::priv_container_from_end_iterator
lib: fix proxy-reference-unfriendly method in node_cloner
lib: core implementation of header_holder in bstbase3
tests: bounded pointers tests for slist, list, (rb/avl) x (set/multiset)
tests: bounded pointers tests for (splay/sg/treap)x(set/multiset)
Merge branch 'header-holder' of https://github.com/mateidavid/intrusive into mateidavid-header-holder
Added support for node and value pointers non-convertible from raw references