Bring dialog boxes in the front when qbt doesn't have focus.

Code inspired by glassez patch.
Correctly resize 'name' column of the content tab. Closes #1360.
Reuse code in AddNewTorrentDialog. #894.

Conflicts:
	src/addnewtorrentdialog.cpp
Correctly restore 'name' column width when loading magnet links in the 'Add new torrent dialog'. Closes #1334.
Fix WebUI sort by size/speed for some locales (with comma as decimal point).
Fix WebUI sort by ratio for some locales (with comma as decimal point).
Sync translations from Transifex.
Update Changelog.
Bump to 3.1.6