MVT with zoom levels

[dbauszus-glx]

It should be possible to define a field which limits a feature based on the current zoom level. For example motorways should be drawn on lower levels than residential roads.

This will also solve issues with complex boundaries. Already simplified features could be shown at lower zoom levels and more detailed representations of the same feature at higher zoom levels.

The field should be defined in the layer configuration. e.g. mvt_zoom_field

If set a filter will be applied to the mvt tile generation, excluding items with values in the defined field which are below the current zoom level. e.g. Secondary Roads should only be drawn at a much higher zoom level than Motorways.