This adds support for selecting the font in ditaa diagrams by specifying
--font-family, --font-size and/or --font-variant in the ditaa() line.
The change is actually taken over from @pepijnve who implemented in
https://github.com/pepijnve/ditaa/issues/1. I extended it for supporting
the necessary flags from plantuml.
new Double and similar got a removal warning in java-17, do Double.valueOf,
Double.parseDouble and similar for other types.
.editorconfig caused some trimming of trailing whitespaces.
remove boxing
