[] allow weasyprint subprocess flags and process timeout via configur…

[kreuzberger]

In rare cases i ran into infinite loops with weasyprint, not seeing any output, not can give any flags, breaking my CI jobs. This was the intention to configure the subprocess to:

• support flags from configuration, e.g. --debug or --verbose flags
• timeout subprocess after configured timeout to avoid stucking in CI jobs

[kreuzberger]

This was a solution/hack for a problem i ran into with massive parallel builds on windows. But this was just a workaround, no good final solution. Still getting timeout errors due to weasyprint.exe running in infinite loops. Single builds of the documents worked as exepected. After playing around i found that this seems to be related to the #25 error, wether or not the "complex" monospace fonts are rendered correctly. After many tests i think best would be to use weasyprint as library not as executable. This seems to fix the issue. So i would close the pull request as "obsolete" adding a new one where weasyprint is used as library

[kreuzberger]

and the hope died after the 10th regression test :-1:

[danwos]

This is really helpful for CI and tests. Thanks for the PR :+1:

Getting a stable run on windows seems to become a tough topic for us. For me, it is yet not clear if it is a general problem with weasyprint or some "buggy" HTML/CSS, which is created by us.