manual watt modus

[weinzmi]

implement a manual watt modus.
Idea - reuse the existing watt.py and yaml

create a manual.yaml file with only one seq:

Prog:
  Seq1:
    Name: Manual watt 
    Description: Manual Watt training
    Watt: 25
    Duration: 3600

[weinzmi]

add a variable to watt output (watt+offset) and get offset from userinput (webserver)