Don't rely on dpkg-parsechangelog to get version.

This utility only exists on Debian based platforms.
Fix issue where incoming chat messages fail when getting called from the same session at the same time (FS#1922).
Fixed typo.
Merge pull request #132 from deathwish/remove-dpkg-parsechangelog-usage

Don't rely on dpkg-parsechangelog to get version.
0.22.7
Make sure to stop stream after testing user media access.
Use correct aspect ratio when zooming in/out of picture.