DVB: Improve compatibility with some BDA drivers after  ada3ea6714e7c5f11e73df27aa7123c5a491e362.

This commit makes the statistic interfaces handling more fool-proof.
Make some strings translatable after d2e7b814e34a99fc71222a34d528cfc193ca4cad.
Scan dialog: Fix translations after clicking "Start" button.
Updated Polish translation.