Tabled tab completion now includes divider row.
Tab completion results for aliases, macros, and Settables wrap long fields.
SimpleTable now accepts blank for the divider character. It is identical to passing None.
Removed --verbose flag from set command so the descriptions always show.

Converted some strings to f-strings.
Fixed some grammar in error messages and docs.
Increased code coverage.

Changed CommandResult.stderr to a str instead of Optional[str]

# Conflicts:
#	cmd2/__init__.py
#	cmd2/argparse_completer.py
#	cmd2/argparse_custom.py
#	cmd2/cmd2.py
#	cmd2/decorators.py
#	cmd2/exceptions.py
#	cmd2/utils.py
#	examples/arg_decorators.py
#	examples/argparse_completion.py
#	examples/modular_commands_main.py
#	tests/test_argparse_completer.py
#	tests/test_argparse_custom.py
#	tests/test_cmd2.py
#	tests/test_completion.py
#	tests/test_history.py