* Rewrite net.dns.resolve on LWIP
* Move IGMP (net multicast) to LWIP
* Cleanup net module
* Move secure connection operations to tls module
* Net module on LWIP
* Server timeout parameter
* TCP hold
* Fixes in documentation
* Documentation fixes
* Note TLS module depends on net
* Add TLS module to user_modules.h
* Callback on connect event
* Fix depends net module on tls module
* Fix unhold exponential time issue
Yury Popov