view, vfilter: Add support for filtering tags and values out of a view, using !tag...

view, vfilter: Add support for filtering tags and values out of a view, using !tag and field!=value.

Note that negated globs are not supported. Would have complicated the code
to add them, without changing the data type serialization in a
non-backwards-compatable way.

This commit was sponsored by Denver Gingerich.