Support `-t` and `-u` commandline filtering options for tagged and untagged collections

[IonoclastBrigham]

These correspond to the ⌘T and ⌘U accelerator keys. This has the advantage of pre-filtering the loaded collection before anything is displayed, and should be much faster than loading a directory and then filtering manually.

Caveats

These options would be mutually exclusive with each other (or at least pointless in conjunction), as well as not making sense with any of -a, -o, -e, -x, etc.

[lehitoskin]

Is the goal to load the search results or display them on the command line?