Allow calculated metrics to refine props and evars in Discover and Data Warehouse segments

It would be helpful to be able to craft segments based on frequency of use and engagement with each section.   At present, we can build segments by including total users of each section, but to really replicate the data coming out of a quant segmentation, some segments need to be further defined (e.g., visitors that had higher than average frequency to the section, or consumed more pages or video in the section).  I understand that we could also create additional success events for each section to arrive at the above targets, however our resources for implementation are limited and it seems that adding the above functionality could be useful for many people and purposes. Thanks for reading!