[Patch] Replace hookUpMapView by attachToMapView

[michael2402]

When supporting multiple (or none) map views, hookUpMapView() is not what most layers need.

I add a new method attachToMapView and detachFromMapView to allow for handling multiple MapViews.

The basic idea is that all you can make your layer extend LayerPainter and add the detachFromMapView and paint method to it the way it was before.

Or you can create a new LayerPainter instance for every map view if you need to cache data that is specific for each map view.

The layer painters are then used to paint the current layer. For now, this is just a call to the old Layer.paint method.

This is currently only added for the Layer class. I want to add it to temporary layers later.

[Don-vip]

In 10458/josm:

fix #13029 - Replace hookUpMapView by attachToMapView (patch by michael2402, modified) - gsoc-core

[Don-vip]

In 10461/josm:

see #13029 - fix javadoc warnings