Version 0.15.2

Features:

• Allow specifying the map's initial maximum bounds in a different GCS (#794)
• Improve setting widget positions (#796)
• Add methods to simplify line geometries (#791)
• Add functions computing spherical and Vincenty distances (#797)
• Add a scale widget (#798)
• Improve the screenshot function by dereferencing CSS urls (#799)

Testing:

• Fix testing with Chrome 65 (#792)
• Add tests for geo.gui.widget and geo.gui.domWidget (#795)

Documentation:

• Enable the color legend example (#790)
• Add a new editor tutorial with HTML and CSS panes (#783)
• Use https urls for openstreetmap tiles in all examples and tutorials (#793)