updated dependencies + conform to API changes
reuse buffers when serving multiple requests to the same client connection

by taking advantage of the fbuf_attach()/fbuf_detach() semantic
store the data in a buffer embedded to the cached_object structure

if it's smaller than 256 bytes. This prevents internal heap fragmentation
if dealing with small data which is loaded asynchronously
store the key in a buffer embedded to the arc_object_t structure

if it's smaller than 64 bytes
make use of the reusable buffer pool available in the queue implementation

since last libhl version
updated libhl