Loads an sample file from 'filename', using the provider identified by 'type'.
static CL_SoundProvider* CL_SoundProviderFactory::load( const CL_String & filename, bool streamed, const CL_String & type, CL_VirtualDirectory directory);
Detailed description:
If the type is an empty string, it uses the extension of the filename to determine what type it is.
The input provider will be used as a the source for filename, if specified.