PinChangeInt.h not found

[keithellis]

Hello all.

I'm just getting started with MySensors.org. I'm trying to flash my ProMini 3v3 with the Serial Gateway sketch with Arduino 1.6.4. on a Mac running OSX10.11.1

I have copied the MySensors library folder into user/documents/arduino/library

I have opened the SerialGateway sketch from File/Sketchbook/libraries/MySensors/SerialGateway

Upon verifying the sketch I get the following error in the Arduino IDE

SerialGateway.ino:52:26: fatal error: PinChangeInt.h: No such file or directory
compilation terminated.
Error compiling.

I cannot find the PinChangeInt.h file in the library. Can someone give me a clue on how I move forward. thank you.
Keith Ellis