Feature request: copy filenames to clipboard and then exit from fpp #438

At the moment, the two options to "use" the selected filename(s) is 1) open them in the $EDITOR and 2) append them to a command that is inserted after fpp prompts for it.

I suggest to add an additional option to "use" of the filename(s): copy the list of filenames to the clipboard and then exit from fpp. The filenames shall be separated by a single space, ready to be pasted on the command line or whenever else.

Moreover, add an option to select the character to separate the filenames (default to single space). NULL-separated would be useful in many cases.

WHY (mainly): allow to use the list of filenames directly within the command line; this allows standard editing of commands, and the saving of the command in the history.