Corrected the support for seeking in wxSoundFileStream.
Added support for seeking in wxMultimediaBoard
Reindentation of the code (conforming or nearly to the coding standard)
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@6291 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775