Add Bluetooth connection request/complete/disconnection callbacks.
Remove debugging from HCI layer, as it is now operational -- add guards to ACL debug statements to reduce logging chattyness so that the overall command sequences can be observed and debugged.
Seperated out Lib components of the incomplete BluetoothHost demo application out into a seperate Lib subfolder.
Changed F_CLOCK entries in project makefiles to alias to F_CPU by default, as this is the most common case.