Especially when instrument preview in file browser dialogs is enabled, this can severely hinder navigation e.g. when clicking on a long MP3 file that is several minutes long. The sample decoding should be moved to a separate thread and not block the UI.

Note that the same code and same memory objects are used for all sorts of other previews in the tree view. For previewing in the treeview this is probably very useful as well, but we need to make sure that all places using this stuff are aware of the threading changes.