The cohort exporter should have support for exporting downstream items
The cohort exporter (see #987) currently takes an item list and export data tables for all items and their parent items.
The functionality should be extended with support for also exporting the child items. The major use case is that it should be possible to select a list of biosource items (=all items in a given release) and then export all child items.
One file for each child subtype should be exported (including splitting of StringTie and Cufflinks). Since the number of child items vary the number of lines in each file will of course also vary and it will not be possible to use line number as a key for matching data across different files. It is of course possible to use item names and split on '.' to find substrings that can be used for matching, but this tend to be difficult since not all items follow the same path in the lab (for example, NeoPrep libraries go directly from RNA to Lib, while other libraries have mRNA and cDNA inbetween). I think the exported files should at least have a "Parent name" column to make the mapping a little easier.