Add a map category

[yohanboniface]

The idea is to allow users to define one or more categories for their map. This may help discovering useful maps, eg. by allowing to filter the search by category, or by creating some pages like "last maps in category x" or "most starred maps in category x".

In my idea, the category list is closed, defined by the uMap instance administrator, and I'm in favor of using a setting, so it's possible to use the translation on the labels (if we use a DB model for instance, we could not use the current transifex workflow).

Here is a first suggestion for the default list (please complete):

• Art and Culture
• Bike
• Environment
• Education
• Public sector
• Sport and leisure
• Travel
• Trekking
• Tourism

[clwacker]

Very good idea. One more suggestion for the list:

• Cultural Heritage & History

[yohanboniface]

Maybe something like "Food" ? I see a lot of maps with local food and farms, and so on.