Added initial (not yet thread-safe) logic to modify the state of a bit on an I/O Expander.
Move methods from I2cController.h to .cpp.
Merge pull request #45 from JustAddWires/DMap

Direct map support coming soon.
Implemented I2C callbacks to allow read-modify-write transactions.
Removed some I2C delays.
Merge pull request #48 from JustAddWires/DMap

Implemented I2C callbacks to allow read-modify-write transactions.