issue-#206 change text formatting from Default Font to Arial

[Josef Templ]

I have created an issue for the text formatting reported by Ivan.

For the issue see https://redmine.blackboxframework.org/issues/206.

For a fix see branch issue-#206.

The diffs don't show the format change.
https://redmine.blackboxframework.org/projects/blackbox/repository/diff?utf8=%E2%9C%93&rev=424eaa44706cb8d9682195acca9967e0758b95bf&rev_to=e4da402c70c1411842165e36e5288935679a3396

- Josef