Expanded ViewScene screenshot functionality--share screenshot as issue

[dcwhite]

Somewhat parallel to #938.

If we add a menu to the VS screenshot button

I can think of 3 options right now to code up:

1. (quick mode--TODO this issue or later) save screenshot to user's desktop using generated filename, no pop-up dialog
2. (current slot behavior) save screenshot after file save dialog input
3. (new feature for troubleshooting, this issue) save screenshot and send in an email message, along with current network state saved as xml attachment, to a certain email address or slack endpoint for sharing/discussion.

This issue is to add the GUI parts. I'm still thinking about the email endpoint, but for now we can send to my work email.