1. A shortcut of 'b' was used as the default binding for passing
comment body text to urlview (this is similar to the default of C-b in
the 'mutt' text email client)
2. The `comment_urlview` SubmissionController function was added to
recieve the SUBMISSION_OPEN_IN_URLVIEWER keypress request.
3. The `open_urlview` terminal function was added to handle the urlview
request. It passes the comment body data to urlview via a Popen
process.
4. A test case was added to ensure this new code path is executed
5. Small formatting changes, mostly line length
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