Improve bug reporter tool

[Tom Goddard]

Port the Chimera bug reporting tool to ChimeraX.

[Tom Goddard]

I ported the gui to Qt and the http request code to submit bug reports to Python 3, and made a slightly modified cgi-bin script to send the resulting reports by email to chimera-bugs.

Still need to add a "Report Bug" button to the error dialog.

[Tom Goddard]

Here are some improvements that could be made to the bug reporter.

1) For very long logs make it an attachment instead of part of the description (Eric request).

2) If they every report a bug with contact name or email then cache those values and enter them whenever the bug reporter shown in future sessions.

3) Ping RBVI server before bug dialog is shown and if it is not responding then report that so they don't needlessly fill out the form.

4) Limit attachment size.

5) Highlight text in dialog that says entering email is needed if they want a response (Eric request).

6) Put more system and graphics info in "Gathered Information" field. Currently we don't show graphics settings as in Chimera bug reporter.

7) Add Mac crash report detection as part of bug reporter bundle. This is a separate MacCrashReport tool in Chimera that should be easy to port.

[Tom Goddard]

Did 2). Added caching of last used contact name and email address.

Did 7). Added crash detection at startup that shows bug reporter if previous ChimeraX use on Mac crashed.