add NewTron theme

- fix: VtmThemes enum
docs
move TagFilter stuff to OsmTileLayer
refactor: TileLoader.createLoader()
get theme from VectorTileLayer, instead of setting it on Loader
refactor: MapTile hold generic TileData - Testing
start TileLoaderHook:

- only create ExtrusionLayers when a BuildingLayer is attached
fixup loader create
add TileData.owner as identifier
fix: inner class should be static
TileData owner should always be a Layer
insert new hooks at front
move Text/Symbol handling to LabelTileLoaderHook