#5 Handle booster with relay setting DSR

[Torsten Schönfelder]

Boosters with relay used for setting the relay seem not to be supported.

The relay will take close to 1 sec after power on the set DSR, but the shortcut should be handled quicker.

Proposal is:
Add a new option that allows to
- watch the DTR line to understand, if the booster should be up
- if DTR is off, allow it for the time given in the option to stay off
- disable booster else
- set on delay equal to off delay, if optin is not given