update desc file generation by MIDIExplorer et al

[adcxyz]

desc files as generated by e.g. MIDIExplorer could be more complete:
example text for all the entries now recommended,
and probably assocArrays instead of dicts so we can maintain a desired order of elements.
(
idInfo: "___",
...
description: [
'key_1' -> (elementType: ... , ...),
'key_2' -> (elementType: ... , ...),
]
)

[adcxyz]

should now do

(
idInfo: "___",
...
elementsDesc: (
    elements: [ 
        (
            key: 'xyz', 
            elemements: [ ]
        )
    ]
)
)

[adcxyz]

First pass if this is done, MIDIExplorer now posts a usable flat list of all elements found.
In a way, it makes sense to keep it that way and not try clever guessing how to organize
the elements found:
The guess will always be somewhat wrong, and for the person making the file,
doing the hierarchy by hand seems the best way to learn how one really wants to think
about the elements and their hierarchical order for the device at hand.
Possible exception: Maybe it would be good to create groups per midiMsgType,
and put blank shared: () entries in each of them.