Fix #505: ‘Copy path’ and ‘Delete’ are too close in the drop down menu

Fix #505: ‘Copy path’ and ‘Delete’ are too close in the drop down menu

https://github.com/BestImageViewer/geeqie/issues/505

This commit attempts to ameliorate this issue by moving the Delete
action to the end of a section and ensuring a divider is immedialtely
below it.