Cat-Printer 0.4.1

Compared to 0.4.0, this corrected a few layout inconsistency,
along with a better monochrome method ("dithering") in frontend,
and "threshold" is now "brightness" for i) it's now really that, and ii) won't confuse non-technical users anymore.

You can also check 0.4.0 release notes / discussion to see what's generally new.

Also something unsaid is 0.4 would reset the settings if you're coming from 0.3. I would keep it occur less in the future.

Please ignore the careless 0.4.0 in file version of git tag tarball...