Robust token handling

-modified complileLine():
-comment definition is now safe (does not fail on short/empty lines)
-uses default String.split()
+the parameterised one behaves differently when passed the empty string
+this version returns the empty list when passed ""
+but locks us in to whatever Python deems to be whitespace...
-robustly detects and handles any number of tokens per line

-added removeComment()
-removes any part of a string after "//"
-may be modified with a global variable to track multi-line comments

-modified program to reflect compiler abilities