View ordering

[Nadia Polikarpova]

All map items (views) are stored in one data structure. In the beginning they are added in the right order (e.g. stations after lines) so that the z-ordering is ok, but if you add city items later the z-ordering can be wrong. Instead we could have a list of lists and some association between the city data structures and those lists, and also maybe a view factory to create views for each city item.

[Nadia Polikarpova]

Implemented a workaround: now on every map update all views are removed and then added again. This is potentially slower, in case you do a lot of updates (of non-mobile objects), but the difference is unnoticeable on existing examples.

[Nadia Polikarpova]

It turned out that the workaround causes a problem if a view if modified (e.g. highlighted), as those modifications are lost after an update.

[Nadia Polikarpova]

Fixed for real now: introduces a figure group for each kind of city objects; those figure groups are added to world in correct order, views only have access to those groups and not to the world.