add nid concept check
refactor all of the cell text and nid read code into RefexDynamicGUI -
which is the thing that all of the cells / columns have reference to.  

This fixes / enables sorting for all of the columns, and should allow
for filtering.
Merge branch 'master' of https://github.com/Apelon-VA/ISAAC.git

Conflicts:
	refex-view/src/main/java/gov/va/isaac/gui/refexViews/refexEdit/DynamicRefexView.java

Also, some other local changes (mostly comments) and some null handling
cleanup in ConceptNode (Because git is silly, and wont let me not-commit
these files after getting a conflict)