Added Lots of Documentation

Added some nice to haves
Improved and Unified General Code Layout

MathKit/MPSumFunction.m

@@ -15,7 +15,6 @@
 
 @implementation MPSumFunction
 
-
 MPFunctionAccessorImplementation(StartExpression, _startExpression)
 MPFunctionAccessorImplementation(TargetExpression, _targetExpression)
 MPFunctionAccessorImplementation(SumExpression, _sumExpression)
@@ -26,11 +25,13 @@ MPFunctionAccessorImplementation(SumExpression, _sumExpression)
     return @[@"startExpression", @"targetExpression", @"sumExpression"];
 }
 
+
 - (BOOL)expectsVariableDefinitionInChildAtIndex:(NSUInteger)index
 {
     return index == 0;
 }
 
+
 - (Class)functionTermClass
 {
     return [MPSumFunctionTerm class];