print median PSD in separate file

The median PSD from the cleaning phase is printed out in a separate file and a factor of (seglen/2) is applied. This file is ready to be passed on LI.

@tyson-littenberg please check and merge

One thing to think about: the LALInference file only gets printed from the cleaning phase. That's 99.9% fine, however I can imagine scenarios where we want to run signal+glitch to get a PSD for offline running. In that case we can do the conversion on the usual output (or modify things for the "offline tag." I think this is fine for now.

mentioned in commit 1b372d3f

merged

mentioned in issue #36 (closed)