ESP3D-WEBUI for ESP3D/ESP3DLib/grblHAL

Update README.md

Change to hard code WebSocket sub protocol

Use ISO_8601 date time format for ESP800
Update docs
Bump version
Build index.html.gz

Merge 3.0 refactoring

## What's Changed
* Complete refactoring using spectre.css and correct Preact API per @alexblog suggestion
* Smaller footprint
* Add support for extensions/pluggins
* Add theme support by using external css
* Remove banner as unnecessary
* Remove information bar and put information to separate page and respective panel
* Add audio and haptic feedback
* Add Repetier / ESP3DLib V2 / Smoothieware / GRBL support
* Split code for 3DPrinter / CNC / Sand Table

## Limitations
* CNC / Sand Table specific UI is still not defined
* Wizard is not implemented yet
* Works with ESP3D 3.0- alpha-2 - no backward compatibility
* Language packs are not ready to be translated yet as UI is not finished

## Discussion / status
[Discussion](#94)

## New Contributors
@alexblog made several contributions like #236

Builds for release 2.1.1

Update README.md

Add support for temperature / positions broadcast

Add support for Flow rate / Feed rate broadcast, initialize Feed rate / Flow rate control if info available
Add rendering for custom command for temperature / position /etc

Create index.html.gz

Update README.md

update version for release