Added networking plugin

For telnet and/or websocket stream communication. Implemented on top of the lwIP network stack. The ESP32 and MSP432EY401/TM4C129x drivers will soon be updated to use this plugin instead of "local" code.

NOTE: Websocket support is to be regarded as in alpha phase. Simple testing is promising though...

plugins/networking/README.md

@@ -0,0 +1,26 @@
+## Networking services plugin
+
+This plugin contains code for "stream based" network protocol support on top of the lwIP TCP/IP stack.
+
+"stream based" in this context means that the HAL entry points for streaming are used as the API \(by dynamic pointer swapping on connect\).
+
+#### Protocols supported:
+
+* Telnet ("raw" mode)  
+* Websocket - work in progress, initial test results are promising.  
+
+#### Dependencies:
+
+[lwIP library](http://savannah.nongnu.org/projects/lwip/)
+
+#### Credits:
+
+Parts of WsStream.c are pulled from [patch 9525](http://savannah.nongnu.org/patch/?9525) by Sakari Kapanen.
+
+base64.c, sha1.c by Brad Conte, pulled from from the same patch as mentioned above.
+
+__NOTE:__ some drivers uses ports of lwIP provided by the MCU supplier.  
+__NOTE:__ this plugin is only for the protocol layer. Driver specific code is required for initialising lwIP and start/stop/polling the services.
+
+---
+2019-11-18