UI updates

• Add CyclOSM layer.
• Add support for bookmarks.

Bugfixes

• Show locate marker above everything else.
• Show difference in edit history also when map settings are changed.
• Fix drawing of lines.

Technical changes

• Refactor layers component so that it can be used on multiple maps.
• Explicitly create database tables with UTF-8.
• Refactor frontend so that it can be used as a library, create FacilMap component that can be embedded and extended inside Vue apps.

Documentation

• Overhaul client API documentation.
• Document Leaflet components.
• Basic documentation of the FacilMap frontend API.
• Improve documentation front page.