Dynamic filters

Merging groups and filters into something the user can define by logically combining base filters. E.g. (start > now-7d) & (name ~ /.*\.zip) & ((status = complete) | (status = running)) would list all zip files that have at least started downloading this week. Possible base filters would include:

* Start date/time of the download
* Status
* Size
* URL, filename (allowing pattern matching)
*..and I am sure the community will come up with quite a few others.