mod_cluster 2.0

Move to nonblocking I/O (multicast logic)

Drop legacy versions (e.g. sar)

Tomcat 9/8.5 support (already wip)

Add CMAKE support to C code part.

Separate C native code and move the C code to ASF?

• remove the slomem code and use the httpd-2.4 code.
• arrange the mod_proxy_cluster to be a simpler loadbalancer.
• remove copy of mod_proxy code.

Project rename

Protocol versioning

etc