Update to OpenLayers 5

• Fixes #9.
• Merge pull request #48 from dpmcmlxxvi/update-ol 2e6ed81
• Update ol documentation. 5f30854
• Update to ol5. 8ffba79
• Merge branch 'master' into update-ol 9943d43
• Fix ol3 to ol5 breaking changes. 42ee3f3

v0.4.1...v0.5.0