Multiple categories selection for uploaded dataset

[jiri-b]

possibility to select multiple categories when uploading my dataset. E.g. I looked for something like restaurants or food (wasn't sure in which category to put the smoke-free bars, so I chose culture-sports-freetime). Later I realised that e.g. in Issy and Athens, the restaurants are listed below "tourism"). A possibility to select multiple categories would solve this, e.g. for the bars I would select freetime as well as tourism