terminal_width can now returns None.

* bzrlib/win32utils.py:
(get_console_size): Fix typo in comment.

* bzrlib/ui/text.py:
(TextProgressView._show_line): Handle the no terminal present case.

* bzrlib/tests/test_osutils.py:
(TestTerminalWidth): Update tests.

* bzrlib/tests/blackbox/test_too_much.py:
Fix some imports.
(OldTests.test_bzr): Handle the no terminal present case.

* bzrlib/tests/__init__.py:
(VerboseTestResult.report_test_start): Handle the no terminal
present case.

* bzrlib/status.py:
(show_pending_merges): Handle the no terminal present case.
(show_pending_merges.show_log_message): Factor out some
code. Handle the no terminal present case.

* bzrlib/osutils.py:
(terminal_width): Return None if no precise value can be found.

* bzrlib/log.py:
(LineLogFormatter.__init__): Handle the no terminal present case.
(LineLogFormatter.truncate): Accept None as max_len meaning no
truncation.
(LineLogFormatter.log_string): 

* bzrlib/help.py:
(_help_commands_to_text): Handle the no terminal present case.