[BT] Code style fix.
[BT] Replace auto_ptr with unique_ptr.
[BT] Use init lists for session settings props lists.
[Util] HasSupportedImageExtension() should query QImageWriter.
[Util] Documented HasSupportedImageExtension().
[Util] Fixed params naming in SysInfo ctor.
[Util] Fixed parameters passing in delegating ctor.
[Util] Documented OSInfo structure.