Add filter-word command

[tstack]

The no longer functioning 'scrub' option would hide redundant parts of the log line (years in dates, log levels). Adding the ability to filter within a line would be good too.

From Kevin Quick:

Have a "filter-word" command. Very similar to filter-out, but
applies to words instead of lines. Maybe "filter-regexp" for
better flexibility, but still intra-line. Useful to eliminate
"noise" on the lines to focus on the interesting portion.

[peteruithoven]

+1

[tstack]

A related request is to allow the line to be manipulated to insert/remove columns.

[tstack]

Gonna say this is taken care of by #412