detachInterrupt() support missing for INT2, INT2 missing for ATmega644

What steps will reproduce the problem?
1. attachInterrupt(INT2...) on an ATmega1284
2. detachInterrupt(INT2)

or

1. attachInterrupt(INT2...) on ATmega644

What is the expected output? What do you see instead?
Case to detach interrupt INT2 is missing from the detachInterrupt() function. 
Additionally, EXTERNAL_NUM_INTERRUPTS in wiring_private.h is not correct for 
ATmega644.

What version of the Arduino software are you using? On what operating
system?  Which Arduino board are you using?
WInterrupts.c in current Github repository (as of 4/5/2012)

The attached files include fixes for the above issues as follows:
* WInterrupts.c: Add INT2 case to detachInterrupt()
* wiring_private.h: Detect (more smartly) EXTERNAL_NUM_INTERRUPTS for 
ATmega644/1284 by checking for the presence of the ISC2x bit definitions (only 
defined for chips with an INT2).
* (bonus) WInterrupts.c: Close Issue 831

Original issue reported on code.google.com by drmn...@gmail.com on 6 Apr 2012 at 3:06

Attachments:

WInterrupts.c
wiring_private.h

anilgkts / arduino

detachInterrupt() support missing for INT2, INT2 missing for ATmega644 #879