cf https://forum.openstreetmap.fr/t/umap-2-3-changement-de-gestion-des-pop-up/23680/3
Trying to make this panel expanded/condenses thing simpler and more intuitive.
It's mode can be set:
- by explicitely setting defaultPanelMode = xxx
- or, if defaultPanelMode is undefined, with sensible default when there is
an onLoadPanel defined, and to respect previous uMap behaviour
- or, if defaultPanelMode is unset, and some feature opens in the panel, it
will be set to expanded (here again to respect previous behaviour
- then, when user change it manually (by clicking on the toggle button), then
we should never change it automatically, and respect the previous mode when
reopening the panel
(We are only talking about the left panel, here.)
Features title may contain variables, which include geographical
ones (center, lat, lon…), and in this case the feature must be
on the map to be able to compute them (eg. the polygon center).
fix#1519
