Some corrections and a build script for documentations

some error corrections with virtual functions, do nothing with avr-gcc-4.6.2 but works with newer avr-gcc Versions. (tested with mighty_twox) but there are more such Errors in code, what i correct next time.

Added a build script for making documentation with doxygen and Graphviz.

sd_crc16 without table, it saves space but is to slow when navigating in sd menu. I comment it out now for maybe later use.

Removed unused memer functions setLED and setLEDs.

Is it a Problem, when I create so many pull requests?
Or can you merge my changes without pull requests?
You can change my commentary, if my english is not the best.