#330 Make assign-confidence capable of parsing search-for-xlinks output files

[William S Noble]

The attached output file shows the seg fault that arises when I run assign-confidence on a search-for-xlinks output file. Besides fixing this seg fault, the program needs to automatically detect the presence of the "p-value" column, and use that as the score (with smaller-is-better=T), and handle additional columns like eta, beta, etc.