Rework backend add MQTT and WebSocket support

* Update back end to add MQTT and WebSocket support
* Update demo project to demonstrate MQTT and WebSockets
* Update documentation to describe newly added and modified functionallity
* Introduce separate MQTT pub/sub, HTTP get/post and WebSocket rx/tx classes
* Significant reanaming - more accurate class names
* Use PROGMEM_WWW as default
* Update README documenting PROGMEM_WWW as default
* Update README with API changes

interface/src/project/LightStateRestController.tsx

@@ -0,0 +1,70 @@
+import React, { Component } from 'react';
+import { ValidatorForm } from 'react-material-ui-form-validator';
+
+import { Typography, Box, Checkbox } from '@material-ui/core';
+import SaveIcon from '@material-ui/icons/Save';
+
+import { ENDPOINT_ROOT } from '../api';
+import { restController, RestControllerProps, RestFormLoader, RestFormProps, FormActions, FormButton, SectionContent, BlockFormControlLabel } from '../components';
+
+import { LightState } from './types';
+
+export const LIGHT_SETTINGS_ENDPOINT = ENDPOINT_ROOT + "lightState";
+
+type LightStateRestControllerProps = RestControllerProps<LightState>;
+
+class LightStateRestController extends Component<LightStateRestControllerProps> {
+
+  componentDidMount() {
+    this.props.loadData();
+  }
+
+  render() {
+    return (
+      <SectionContent title='REST Controller' titleGutter>
+        <RestFormLoader
+          {...this.props}
+          render={props => (
+            <LightStateRestControllerForm {...props} />
+          )}
+        />
+      </SectionContent>
+    )
+  }
+
+}
+
+export default restController(LIGHT_SETTINGS_ENDPOINT, LightStateRestController);
+
+type LightStateRestControllerFormProps = RestFormProps<LightState>;
+
+function LightStateRestControllerForm(props: LightStateRestControllerFormProps) {
+  const { data, saveData, loadData, handleValueChange } = props;
+  return (
+    <ValidatorForm onSubmit={saveData}>
+      <Box bgcolor="primary.main" color="primary.contrastText" p={2} mt={2} mb={2}>
+        <Typography variant="body1">
+          The form below controls the LED via the RESTful service exposed by the ESP device.
+        </Typography>
+      </Box>
+      <BlockFormControlLabel
+        control={
+          <Checkbox
+            checked={data.led_on}
+            onChange={handleValueChange('led_on')}
+            color="primary"
+          />
+        }
+        label="LED State?"
+      />
+      <FormActions>
+        <FormButton startIcon={<SaveIcon />} variant="contained" color="primary" type="submit">
+          Save
+        </FormButton>
+        <FormButton variant="contained" color="secondary" onClick={loadData}>
+          Reset
+        </FormButton>
+      </FormActions>
+    </ValidatorForm>
+  );
+}