Change over AVRISP project to have both hardware USART and software USART modes for the PDI protocol, when enabled. Fix up PDI initialisation routines.

Fix PDITarget_ReceiveByte() not discarding the start bit properly, and reading in the bits inverted and in the wrong order.

Fix inverted bit-banged USART logic in the AVRISP project for PDI programming. Add a delay to the clock toggling in the AVRISP project to ensure that the programming speed does not exceed 10MHz under any conditions to satisfy the limits in the datasheet for all target voltages. Fix incorrect pin being used as the DATA in in PDI programming mode.

Fixed HID Parser not distributing the Usage Min and Usage Max values across an array of report items.

Added new HID_ALIGN_DATA() macro to return the pre-retrieved value of a HID report item, left-aligned to a given datatype.

Added new PreviousValue to the HID Report Parser report item structure, for easy monitoring of previous report item values.

Make sure the protocol handler files are included in the Doxygen documentation of the AVRISP project.

Document the PDI programming routines implemented so far in the AVRISP project. Add ability to selectively disable ISP programming support in addition to the existing ability to disable PDI programming support.

Started implementing the low level PDI protocol in the AVRISP project, for XMEGA device programming.