DM running meeting contribution

[Laurent Michel]

Dear DM

Unfortunately, I couldn't attend  the running meeting because of a friend's funeral.

I apologise for this long message but it could feed the MANGO item of the agenda.
If that occurs I look forward to read the meeting notes and to reply to them

I would like first to thank the active contributors (especially Gilles, Mark T and CD)

My report:  

STATUS OF THE DOCUMENT
- I addressed most of the issues (#63 ->73) in the last PR (#76).

IMPLEMENTATION UPDATE
Mark CD has pointed out some omissions and inconsistencies that need to be addressed.
I don't have the manpower to update the reference implementations or the services that 
provide them along with the GitHub issues. 
I'll do it once we've agreed on the model structure.

GLOBAL ISSUES THAT NEED TO BE ADDRESSED
1- Label class:   
    o  This property needs to be either removed or linked to a vocabulary.
    o  My point of view: Having a label as a property allows MANGO objects to be annotated globally. 
        This is not a strong requirement, so I'm happy with both options.

2- Referring to draft vocabulary
    o Calibration levels refer to a draft vocabulary
    o  My point of view: This is not a problem for MANGO, since the use of vocabularies allows 
        the set of accepted words to be able to evolve independently from the model version. 
        It is therefore not necessary to approve the vocabulary before using it in the model.

3- Use of MeasDM errors
    o MANGO includes error classes imported from MeasDM, but extended with a confidence
       level and a statistical distribution (cross match use-case).      
    o In addition, I've redesigned the Ellipse class to avoid associating roles with positions in a coordinate array,
       which is a burden for both annotators and clients.
    o My point of view: These MANGO error classes address the EpochPosition use case and there is 
       no rule that says the MANGO use cases must be enclosed in those of Meas/Coord. 
       So moving them back to Meas before setting MANGO as an RFC is something I really want to avoid,
       as this would open a Pandora's box with little benefit.      
    o  My proposal (see #76) : 
        - Update MANGO to only use the specific error classes (mango:errors*)  in the EpochPosition context,
        - Break the inheritance link between meas:Uncertainty and mango:PropertyError
        - use the abstract class Meas:Uncertainty for the errors in the other places (photometry)

Congratulation for those who reached the end.

Laurent