Updated TODO list.

TODO

@@ -19,4 +19,9 @@
 - Change integral representation in parser so that _ and ^ bounds are printed correctly by line printer.
 
 - Rewrite unit tests to use improved line printer syntax.
+
 - Add notation "1 1/3" for 'int with fraction' leafs, and rules to rewrite them to fractions and back.
+
+- frontend: replace 'dx' with '(dx)' with regex before sending to parser
+
+- "sin^2 x" is supported by parser, but not yet by line printer.