Implementing interruptus INT2, INT3 and INT6 on leonardo [imported]

[cmaglie]

This is Issue 988 moved from a Google Code project.
Added by 2012-07-19T22:22:46.000Z by jakobmoe...@gmail.com.
Please review that bug for more context and additional comments, but update this bug.

Original labels: Type-Enhancement, Priority-High, Component-Core, Component-ATmega32U4

Original description

What change would like to see?
Implementing interruptus INT2, INT3 and INT6 on Leonardo.

Why?
Have more interruptus, when Serial1is not used, and i2c is.

Would this cause any incompatibilities with previous versions? If so, how
can these be mitigated?
Nope

[Fede85]

INT2 and INT3 where added by Lauszus, see the commit: dab4d8d