Test how we wrap long lines a bit
Rewrite quoteforpo() for performance

This way we only escape the whole string once. We now wrap the escaped
text, instead of escaping the wrapped text, which is closer to what
gettext does.
Allow up to 77 characters per line

Now that we wrap escaped text, this brings us even closer to how gettext
formats lines.
Update test to conform to msgcat

Tested with msgcat version 0.18.2
Merge https://github.com/translate/translate