Is your feature request related to a problem? Please describe.
I sometimes have opened a couple of files across multiple domains, which are huge and take a long time to build the search index (#548).

Describe the solution you'd like
I would like to add a file to the current lnav session, without quit and rebuilding the index for all other files by adding the additional file to the command line.

Describe alternatives you've considered
In the TAB Files menu there is already SPACE to hide individual logfiles from the display, but adding additional files and removing them from the current session completely is not available as a TUI menu option.

Additional context
Add a / DEL to the TAB Files menu to add files using a small file browser or tab expansion Readline input.