Major structure changes

* new location for InterruptManager
* drivers now under avr-halib/drivers/(avr|ext)
* overall consistent coding style
* removed lots of whitespace characters
* all examples compiling
Comments and Structure

* Created placeholder comments for all undocumented things
* Some additional structure changes
Merge pull request #4 from apfohl/structure

Finished Refactoring of AVR-Halib to new driver configuration structure