gstreamer/gst/spectrum

This is a simple, rather lame spectrum analyzer made from the fix_fft.c
code, as found I think in xmms-0.9.1 (the 75-wide output sounds like xmms
to me), which is actually written by other people (see fix_fft.c for
credits).  It worked last time I had GiST working, which was a while ago.
Yes, GiST is not included here yet, it will be in 0.1.0.