Make a way to report a bug from the application

[vozhyk-]

This can be a button that doesn't overlap with the views created by the visualizer.

It should at least make a package with the assist structure and screenshots (as in #1). It could also send the package automatically, or provide a "share" button for sending it in any chosen way.

[vozhyk-]

Now it saves a screenshot (and the assist structure) every time it's called if the WRITE_EXTERNAL_STORAGE permission is allowed manually from system Settings.

This is undesirable for an end user because:

• It saves a screenshot in a public location on disk every time.
• The user has to know how to grant the permission (#6).
• The user has to find and share the structure and the screenshot manually.
• This is only enabled in debug builds.