Partial fix to running in non-interactive mode

[walterbender]

• Plugin code requires access to GConf client, even in non-interactive mode
• Don't try setting plugin menu in non-interactive mode
• Run from "button press"

These patches are related to https://github.com/sugarlabs/turtleart-activity/issues/30 After applying these patches, the output is now created, but several problems remain: (1) in non-interactive mode, the output is created, but it is blank, even though the code is run (2) in interactive mode, the filename returned from the file selector is blank, so no output is created

[quozl]

Ah, I saw gconf and remembered the other pull request. Now that https://github.com/sugarlabs/turtleart-activity/pull/52 is merged, please rebase?

[walterbender]

Fixes #30 The non-interactive output is appearing correctly. I will open a new issue regarding the file selector bug mentioned above.

[walterbender]

Fixes #56 There was a missing .OK to the response check in the dialog. Seems to work now.

[walterbender]

There was an error in the Gio.settings call for power left over from the GConf code.

[walterbender]

A few more odds and ends missing from the GTK3 port. Also, fixed #46

[walterbender]

Caught a few more places where the toolbar icons were not being set up properly.

[walterbender]

Addressed fullscreen problem referred to in #44 by forcing resize of canvas vbox (both when entering and exiting fullscreen)

[quozl]

Reviewed to 2781942. Want merge yet?

[walterbender]

I think this is ready to merge now... the fix to settings resolved a problem I had encountered with my fix to #30

[quozl]

Reviewed. Tested on Ubuntu 18.04. Tested for #44. Merging.