If user throttles receive by setting recv_mbuf_limit,
after the net interface reports connection as closed we must wait
for data to trickle through before disposing of it.
There can still b data in the buffers (e.g. SSL).
CL: mg: Ensure that user sees all the data before connection is closed
PUBLISHED_FROM=22be0fa368950a9fdb03cfb00febc7c0a1674b01
* Change return type of mg_mgr_poll to return number of events
* Add mg_mgr_min_timer
* Refactor main poll loop to remove LwIP-specific stuff
CL: Refactor mg polling
PUBLISHED_FROM=dc94618b32fa3c84a2f053bd04d134297780ec82
Set CLOSE_IMMEDIATELY flag when destroying conn.
This avoid some races in LWIP adapter.
CL: mg_lwip: Fix race during clean conenction teardown
PUBLISHED_FROM=5c67982390dfaf83527e85d1291f64c6050aa932
A major cleanup, disentangling net_if and ssl_if.
Pulled a lot of common logic into the core and reduced size of net_if implementations.
CL: Mongoose net_if and ssl_if refactoring
PUBLISHED_FROM=29bd4dcb264a1fd96b3dd164e2d880e1c2c0921e
Sergey Lyubka