Fixed font sizes look bad under different resolutions

The text in the following places have a fixed size:

* „Torrent file creation” dialogue title;
* „Add torrent links” dialogue title and „Both HTTP…” below;
* „Requires restart” (next to „User Interface Language”) under Options/Behaviour;
* The whole description from the About dialogue, and also „Name”, „Country” and „E-mail” under About/Author.

Fixed sizes look bad under too low or to high resolutions and offer no easy way out of this problem.

Please alter these captions so that their size will be set relative to the default font size, which can be configured by the user.