Port TWI to new style hw naming API.
Fix a few cases where debug output was produced without DEBUG_TWI set.
Refactor timer API to follow named ports approach as outlined in #20
Port examples of timer usage to new API
Fix some typos that slipped into some of the timer definitions.
Added gitignore to cover binary files.
Fixed compile error.

ADC_REFSEL_VCC_gc is actually ADC_REFSEL_INTVCC_gc
Merge pull request #27 from thewizzy/master

Fix compile error adc.c