Removed completed TODOs.

DG_Approximation.py

@@ -8,10 +8,7 @@ TODO: Contemplate separating cell average and reconstruction calculations
     completely
 
 Urgent:
-TODO: Hard-code simplification of cell average/reconstruction in basis -> Done
-TODO: Add documentation to _calculate_reconstructions() in Basis -> Done
 TODO: Investigate protected vs. public variables -> Done
-TODO: Adapt docstring to uniform standard for colons -> Done
 TODO: Investigate decorators and properties
 TODO: Investigate how to make variables read-only
 TODO: Make basis variables public (if feasible)