Optimize for mobile devices

[Istador]

This should not change anything for the normal desktop mode (and tablet mode?).

Remove:

• Zoom buttons
• Fullscreen button
• Panel that displays the mouse coordinates

Change:

• Collapse the layerController.
• Adjust the size of the layerController to be readable.
• Adjust the size of the popups to be readable.
  • ... or even decouple them from the map as an own fixed <div> overlay or modal.
• Offer @2x tiles (512x512 instead of 256x256)
  • See Retina support commenthol/gdal2tiles-leaflet#6
  • I already tried this, by changing 256 to 512 in the source code of gdal2tiles-leaflet.
  • Alternative to rendering twice: set L.tileLayer's tileSize to 128

[Istador]

Increasing the priority of this issue.

About ~40% of the wiki users use mobile devices.
But, I don't know any concrete percentages for users of the map.