LED strip designer context menu. Fix critical unicolor averaging bug.

[awawa-dev]

Allows to customize the LED strip geometry. Right mouse click on the selected LED:

1. Move single LED
2. Edit the LED properties (location/size). Changes are previewed live before saving.
3. Disable/enable selected LED. The LED is still transmitted but its color is set to black. It allows HyperSerialESP32 / HyperSerialEsp8266 to drop "enabled/disabled first LED" version firmware, because now it can be set in HyperHDR.
4. Permanently delete the LED from the strip. It won't be used anymore so next LED in the strip takes its place.
5. New zoom button to help design geometry for high density LED strips
6. CTRL pressed while clicking right mouse, selects the object below instead of the top-most.

Critical bug for unicolor averaging was fixed