FrequencyTimer2

 Modified by Tim Barrass, June 14 2013
 - added support for ATMEGA32U4 processors (Leonardo,Teensy2.0)
   using Timer 4 instead of Timer 2
  
- Includes updates by Paul Stoffregen, paul@pjrc.com
  for compatibility with newer hardware and Arduino 1.0

  
Original Readme:
Update code from http://www.arduino.cc/playground/Code/FrequencyTimer2 for use with Arduino 0018 and the ATmega328 chip.