MTsat model: Add MTR as an output

[mathieuboudreau]

This should be quit simple to implement, and would be quite useful as many users looking into MTsat are likely interested in also computing MTR for comparison / to report.

[agahkarakuzu]

Only possible when TRs are matching, and should not pop up a dialog box to ask whether the user would like to calculate mtr.

I think an options panel checkbox that becomes available when PDw MTw TRs match.

Happy to review the pr if you'd like to implement.

[jvelazquez-reyes]

Let me implement it if @mathieuboudreau has not done it yet.

[agahkarakuzu]

Sure! You can take a look at the qsm module to see how to manage conditional GUI behaviour.

[mathieuboudreau]

Sounds good @jvelazquez-reyes ! I hadn't touched it yet