#81 sending data into info panel

[rno]

it would be useful if the result of programs could be sent to the info panel, adding to its default content.

maybe with adding some Start Mode / command return option: terminal / internal viewer / info panel,
or maybe a special send_info_panel_command

-with some filetypes
could display metadata view
dimensions of pictures
time length with video
lint results
...

-with any files
I would find useful with things as filesystem extended attributes.

-with any button
as a way to return info only while using the button.