Update license in a copy-edited file header

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Add legacy-compatible editor

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
WIP Exclude the script templates from getting license headers

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>