Improve autofilters

[Don-vip]

Autofilters have been implemented in #14929.

The feature can be enhanced:

• allow users to define their auto filters through the filter dialog
• provide better/faster access to change the current autofilter (maybe in the visibility menu of the layer panel)
• allow non-numeric values
• remove the zoom parameter?
• document the whole thing on the wiki Done.
• see #17436

[Klumbumbus]

I startet docu at Help/Dialog/Filter#Autofilters and Help/Preferences/Display#OSMData

[alarobric]

The layer autofilter shows only the specific layer selected and does not work with multiple values.
For instance when 1 is selected, then objects with layer=1 will show, but objects with layer=1;2 or 1-2 will not.

Great new feature though - very helpful.

[Zverikk]

Creating new objects with an autofilter enabled is impossible: they immediately disappear, since they don't have the tag. Maybe the autofilter should include also new untagged objects.

[Klumbumbus]

Ticket #17436 has been marked as a duplicate of this ticket.

[Klumbumbus]

The zoom parameter doesn't work as expected. After you once reach the min zoom the filterbuttons are displayed and they stay there even if you zoom out. The only way to disable them is to zoom out, move data out of the mapview and zoom in.

[Klumbumbus]

Here is a small patch that adds some more keys as autofilters and a space before the [ (for prettiness).
However buildings:levels doesn't work. When activating an error pops up. It seems the : marks the end of the key and puts e.g. :levels=3 into the value. I tried "building\:levels", "building\\:levels" and "building" + ':' + "levels" but none worked without compiling or UI errors...

incline doesn't work as well, (I copied the syntax from maxspeed), maybe % has special powers here too.

So, if someone please could review before commiting that would be nice :)