Improvements to Maps

[slomo]

• [x] make attribution configurable
• [ ] validate GeoJSON (in GeoJSON field)
• ~~rethink if we actually want GeoJSON, or store Points and MultiPolygons in Leaftlet representation~~
  • we want to stick to GeoJSON (decided in Scrum of Scrums)
  • was only an option to simplify validation
• [x] document isMarkerInsidePolygon algorithm properly
• [x] replace view mixins for list and detail with template tag to use in detail and list view
• [x] rename display_points attribute from point to points
• [x] don't use map_url and base_url as synonyms
• [x] prefix all settings value with A4 or A4_MAPS
• [ ] set a better default help text for GeoJSONField
• [ ] do not hardcode height
  • add as optional parameter to template tag and widget, with old value as default, and none if None
• [ ] consistent usage of form controls in different templatetags/widgets (display_points currently uses a custom solution)
• [ ] Show rates in pins only if the rating feature is enabled

[xi]

I worked on the height in 4198eaf but we could not agree on a solution yet.

[fuzzylogic2000]

partly done