- use shutil.get_terminal_size() in Python 3.3+ to determine the size of the terminal, which produces more accurate results than the previous method.
- introduce new PY_IGNORE_IMPORTMISMATCH environment variable that suppresses ImportMismatchError exceptions when set to 1.
- add TerminalWriter.width_of_current_line (i18n version of TerminalWriter.chars_on_current_line), a read-only property that tracks how wide the current line is, attempting to take into account international characters in the calculation.
Signed-off-by: Pierre-Yves <pyu@riseup.net>