removed an obsolete note
allow to attach an external buffer to an existing fbuf
try using a pool of reusable buffers in both queue and refcnt

to avoid allocating/releasing a big amount of small objects which
may fragment memory wasting precious space
just a note
allow to set the size of the reusable queue of wrapper structures at creation time
new_node() now requires a third argument

as an optional private pointer passed to the terminate_node callback