Nested tags support

[Qronikarz]

Probably the most important function that needs to get added. It was worked on from the start, but it was too complicated.

Nested tags should also be possible to search by their parent tag for example: "lake" could be automatically searched with "water". "Lightbulb_on" should be also searchable by searching "lightbulb".

This would allow to make big databases easier to work with and allow to tag media very precisely, but still searchable by easier tags.