aio: 1st stub libuv bindings
more aio work, init_loop, tcp_connect, test
add more docs
aio: more callback work
add PN_IS_FFIPTR (foreign ptr)
aio: tcp_connect6,pipe_open,pipe_bind,pipe_connect,stream_write
aio: udp_open,udp_bind,udp_bind6,udp_getsockname
aio: more methods, provide larger aio_ wrapper structs passed around

add P and cl to our aio_T_s structs, for callbacks.
aio: init methods called in constructor, removed
add more callbacks, do not create a new cb request/handle, reuse it