concatenate multiline suggestions

[marcomeyerVFX]

this was mentioned in #16 but doesn't look like it's implemented yet.
Many papers have their titles split over multiple lines.
So it would be nice to also allow selecting multiple lines from the suggestions and concatenating them together as the new filename.

[kepler471]

I have come across this a lot. I end up having to select one line, and re-write the contents of the next line.

Maybe one of these solutions could work:

1. Holding down a modifier key when a suggestion is selected, and then pressing an arrow key, selects multiple lines. The lines are concatenated as the new filename. It may be difficult to pick a modifier as different terminals might handle inputs differently. This method also limits the order

2. Add a new key binding which "marks" a selected suggestion. Moving the selection to a different suggestion keeps any previously marked suggestion in the new filename, and adds the new selection to the end of that text. The "mark" key can be pressed again to lock the new selection in the new filename. This way you could build a filename from different selections of lines in a custom order. One example where this could be useful is where pboy has picked up the journal name for a paper, and a user would like to the filename to be "JOURNAL_NAME PAPER_NAME.pdf". A "release" or "unmark all" key might also need to be added, to reset the filename.