Improved Model

Added Keyboard Selection Support
Added Mouse Selection Support
Added Keyboard Editing Support
Corrected Some Bugs
Abstracted the Layout System further
Added Functions Button (test)

MathPad/MPSumFunction.m

@@ -104,6 +104,7 @@
 }
 
 #pragma mark Working With Functions
+/*
 - (BOOL)isEqualToFunction:(MPFunction *)aFunction
 {
     if (![aFunction isKindOfClass:[MPSumFunction class]]) {
@@ -117,7 +118,7 @@
         return NO;
     }
     return [self.sumExpression isEqualToExpression:sumFunction.sumExpression];
-}
+}*/
 
 - (NSString *)description
 {