Timer library for configuration and dynamically allocating (and deallocating) timer interrupt handlers (overflow and compare match) [imported]

This is [Issue 169](http://code.google.com/p/arduino/issues/detail?id=169) moved from a Google Code project.
Added by 2010-01-03T23:18:20.000Z by [dmel...@gmail.com](http://code.google.com/u/107726014984682000895/).
Please review that bug for more context and additional comments, but update this bug.

Original labels: Type-Enhancement, Priority-Medium, Component-Core, Milestone-Post-1.0
### Original description

**What change would like to see?**

The core should define the timer interrupt handlers and provide an API for registering a listener.

**Why?**

For example, the Servo library and the tone() function can't both be linked into a sketch because
they both define a timer 1 comparison interrupt handler.

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

There may be some timing issues.