Added Lots of Documentation

Added some nice to haves
Improved and Unified General Code Layout

MathKit/MPParenthesisFunction.m

@@ -18,16 +18,19 @@
 
 MPFunctionAccessorImplementation(Expression, _expression)
 
+
 - (NSArray *)childrenAccessors
 {
     return @[@"expression"];
 }
 
+
 - (Class)functionTermClass
 {
     return [MPParenthesisTerm class];
 }
 
+
 - (NSString *)description
 {
     return [NSString stringWithFormat:@"(%@)", self.expression.description];