yet another rehash on evo/contig

* reintroduced normalizations on contig past, future, evo because using the cost
sum wasn't cutting it -- that was a bias for placing tracks of a certain size
and we were losing some selectivity on contigous regions in those routines
* now after taking the diffs, and using the original sign from C, we take the
inverse i.e. we are interested in all contigous elements where there are no
changes