Testing that the changes fix what was raised in ISA-tools#509.

Changed the added test to be more realistic. Had to track name columns like Data Transformation Name so values would be handled correctly.

Removed code using ' File' to find data nodes. Added comments and broke up code to be more readable and understood.

test_core had to change because the config file in the test data changed.

validate/test_core mtbls1846 lost all of the errors for middle initial being required, but is no longer required. Added validate_first=False to some conversion tests so they run faster. assert_tab_content_equal in utils.py was not checking things correctly. Lists of dataframes cannot be sorted without defining a "key" parameter. I simply removed the sorting and added returning False on an error rather than True.