high level mode styling function

[eroux]

This is a kind of step 2 to #756, the idea is to have a high level function that allows the styling of the mode according to different configurations, with one for modern Solesmes books and one for the 1934 Antiphonale Monasticum, which has some features difficult to handle with the current code, like some modes completely in italic. I didn't fully understand yet the way things are organized in the different models, so I need to make some further research about this to specify the behavior better. But it could be done separately from Gregorio, maybe a sample configuration in tips and tricks for instance... In fact I think what would be best would be that someone which a good knowledge on this topic (I have none!) and a little time can participate in some discussions (in broken English) with my contact at Solesmes... Who would be interested?

[henryso]

I admit to having no knowledge on this topic either.

[henryso]

Per @eroux (https://mail.gna.org/public/gregorio-devel/2016-05/msg00018.html), postponing this:

#998 - High level mode styling - The requirements for this are not
clear and no one has volunteered to work with Élie's contacts at
Solesmes. I am willing to give this a shot, though I really don't
know much about mode styling and I really only understand English.

I almost forgot about that... well, there are so many discussions with
Solesmes right now that adding this one may be too much... so if it's
not ready, we can postpone it..

[henryso]

@eroux Any update on this? How should we proceed?

[eroux]

sorry, no update... @BrRoman maybe you'd be interested?