Renaming prefixes from "ana" to "rel".

"ana" could be used for any analysis. "rel" is more specific for my
relevance analysis. This will make my life easier in the future, so better
change now.
Cleaning up the AnaRelevance trf file.

Before I may start implementing my analysis, I'm cleaning this, and leaving
only some of the bits I believe will be the same.

Some bits, such as the option handling, were removed but may be re-added later
if necessary.