Improve code readability a bit

NSData+SA_NSDataExtensions.m

 		[self getBytes:terminated_string_buffer length:self.length];
 		terminated_string_buffer[self.length] = '\0';
 		
-		return [NSData dataWithBytesNoCopy:terminated_string_buffer length:self.length + 1 freeWhenDone:YES];
+		return [NSData dataWithBytesNoCopy:terminated_string_buffer length:(self.length + 1) freeWhenDone:YES];
 	}
 }
 
 		char* unterminated_string_buffer = malloc(self.length - 1);
 		[self getBytes:unterminated_string_buffer length:self.length - 1];
 		
-		return [NSData dataWithBytesNoCopy:unterminated_string_buffer length:self.length - 1 freeWhenDone:YES];
+		return [NSData dataWithBytesNoCopy:unterminated_string_buffer length:(self.length - 1) freeWhenDone:YES];
 	}
 }