Pipeline: changes to tag/class counting

[AlexTate]

Repurposing Tagged Counting
The Tag column will be renamed to Classify as... and will be used to apply a user-defined class to features that match the rule. Each feature will be counted on a feature-class basis, just as they are now with feature-tag counting. tiny-count will no longer determine feature class from Class= attribute. The Tag and Feature Class columns of the output counts table will be one and the same. This removes a significant burden from the user for annotating their GFF files with a Class= attribute, which is a particularly arduous task for researchers that don't have a coding background. The values provided in the Classify as... column will serve as group names in class-related plots.