header displays and queries

The t, c, d, f, p and r commands will soon be displaying header values.

We already have the ability to select by header, now its time to support queries.

A command "t * phone=" lists all topics with a phone header. I want to extend this syntax like this: "t * phone= phone?". This would list the topics that have phones and display the phone number as well. Adding additional name? arguments to the command will add additional columns to the display.

And when there are no name? arguments, then all headers will be displayed as name: value pairs.

Hopefully I can get this done this weekend, depending on power.