Merge fade2 with speed2

[emontnemery]

Description:

Merge fade2 with speed2:

• speed2 0 disables fading
• speed2 <1..40> enables fading, with speed set to 1..40

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 on Tasmota core ESP8266 V.2.7.4.9
• The code change is tested and works on Tasmota core ESP32 V.1.0.5-rc6
• I accept the CLA.

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