Updated FindMagnum.cmake from Magnum repository.
Initial support for AudioImporter plugins.
JpegImporter: no need to allocate this on heap.

It's like writing `new char*(new char[35])`. Just don't.
TgaImporter: minor cleanup.

Reset back to default packing (it's 8, but this looks better like
default).
New plugin WavAudioImporter.
Remove this old cruft.

Not relevant anymore.