Added Change Notifications to MPExpression, MPMutableExpression and MPFunction

Removed -beginEditing and -endEditing
Optimized -fixSymbols
Updated Project File

MathPad/MPFunction.m

@@ -8,8 +8,9 @@
 
 #import "MPFunction.h"
 #import "MPExpression.h"
+#import "MPRangePath.h"
 
-#import "NSIndexPath+MPRemoveFirstIndex.h"
+#import "NSIndexPath+MPReverseIndexPath.h"
 
 @implementation MPFunction
 
@@ -156,4 +157,16 @@
     return 0;
 }
 
+@end
+
+@implementation MPFunction (MPDisplayExtension)
+
+- (void)symbolsChangedInRangePath:(MPRangePath *)rangePath replacementLength:(NSUInteger)length
+{
+    NSUInteger index = [self.parent indexOfSymbol:self];
+    NSIndexPath *newLocation = [rangePath.location indexPathByPrecedingIndex:index];
+    MPRangePath *newRangePath = [[MPRangePath alloc] initWithLocation:newLocation length:rangePath.length];
+    [self.parent symbolsChangedInRangePath:newRangePath replacementLength:length];
+}
+
 @end