Check if links and all are accurate, based on the new navbar of the homepage

Create a new menu to export all data from the SQL database to CSV, so that users can import that data to other software easily.

In the Readme file, two links are supposed to link to contribution guides but are dead links as the former wiki has been closed/removed.

https://github.com/ekylibre/ekylibre/edit/master/README.md#L18

• Guide (Français)

https://github.com/ekylibre/ekylibre/edit/master/README.md#L38

• See our conventions ([Français](https

The documentation mentions the configuration for iOS is not needed anymore, but when building for iOS I got an error that the Fabric key was missing from info.plist dict.

I managed to find the needed info.plist code in an older version of the readme.

I'm using the @next version.

User can be looses sometime on the map view and would like to center back on his position.

Just add a button to locate on user position.