Add favicon on browser

[barbudor]

Description:

Related issue (if applicable): fixes #4830

Add a favicon directly encoded in base64 in the HTML header (not served through the webserver)
May be not the most pretty tasmo'art but compact (16x16, 16 grey levels).
Only cost 256 bytes of flash due to unishox compression (🙏 @s-hadinger )

Needed a small change in html compression tool to support string with // inside. => @s-hadinger
(replaced the split() with a simple state-machine parser)

@gemu2015 could you please check that I've not broken SCRIPT_FULL_WEBPAGE please ?

Checklist:

• The pull request is done against the latest development branch
• Only relevant files were touched
• Only one feature/fix was added per PR and the code change compiles without warnings
• The code change is tested and works with Tasmota core ESP8266 V.2.7.4.9
• The code change is tested and works with Tasmota core ESP32 V.2.0.2
• I accept the CLA.

NOTE: The code change must pass CI tests. Your PR cannot be merged unless tests pass

[arendst]

Thx. As the icon is actually black and white do you see a chance to lower it's color depth from 16 gray scale to 1 gray scale?

I don't use compression so for me it adds 400+ bytes bogus information.

[s-hadinger]

Awesome!

[s-hadinger]

Black and white would make it ugly since there would be no dithering.
What about a #ifdef?

[arendst]

I love #ifdef.

[barbudor]

Hi @arendst
Reduced to 1 bit which move the HTML cost from 488 down to 328 (-160 bytes)
No gain on compressed, still 256 bytes.
Aliaising is not as bad as I would have expected

Indeed the browser or windows is doing some dithering on its own

I added #ifdef USE_WEB_FAVICON
But because compressor script ignore preprocessing it will work only for uncompressed.
When using unishox, favicon will always be included.

[arendst]

Thx. Will chk today

[InHi66]

i do it this way:

in xdrv_01_webserver.ino

i add at "const char HTTP_HEAD_STYLE3[]"

following

</style>""" & vblf & " """"" & vblf & vblf