Setting the handle callback allows your application
to take care of network events for the connection.
Look at the connection state and flags to determine
if read/write is possible and go from there.
See kore_connection_handle() for more details.
* The cli tools must know when building as KORE_NO_HTTP.
* Reshuffle some structs around to avoid forward declarations.
* Move wscbs under !KORE_NO_HTTP as its for websockets.
* Remove unused members from struct connection.
Applications that use the connect callbacks for new connections
must now set the connection state themselves, see nohttp example.
This basically turns off the HTTP layer for Kore. It does not
compile in anything for HTTP.
This allows Kore to be used as a network application platform as well.
Added an example for this called nohttp.
Other changes that sneaked in while hacking on this:
* Use calloc(), kill pendantic malloc option.
* Killed off SPDY/3.1 support completely, will be superseded by http2
Note that comes with massive changes to a lot of the core API
functions provided by Kore, these might break your application.
