The Audio::Loader class is able to load different types of audio files
by using a generic plugin interface for all file formats. Every new
loader will have to derive from Audio::LoaderPlugin to provide a common
API.
This makes it easy to add support for more audio file formats in the future.
Previously 4 bytes at once were read and compared to the string
"DATA". This worked when the DATA marker was aligned on a 32-bit
boundary relative to the start of the file. However, this is not
guranteed to always be the case, and for some files the loader
would just keep searching for the marker.
