Show "%of gaps in assembly" in extended table

[ad3002]

"# N's per 100 kbp" is too boring to recompute in %gaps in assembly, in some eukaryote assemblies it can be more than 10%. And as I know biologists simply don't understand what is the meaning of "# N's per 100 kbp" and remove this metric from results. However, this metric has the same importance as N50/L50 for interpretation results including genome annotation results, e.g. a lot of gaps => overestimation of genes number.