FF v1.5

. moved ffurl and ffhttp into directory net/
. atomic functions ffatom_*
. DNS functions ffdns_*
. binary tree and red-black tree functions ffrbt_*
. ffhttp_ifnonematch(), ffhttp_range(), ffhttp_chunked
. ffip4_*, ffip6_* functions
. ffjson_addv()
. ffutf8_len()
. parser with scheme: handle return value from handler function on close context
. parser with scheme: handle FFPARS_FCOPY flag before calling a value-handler function