Enables checksum checking when enabling reception.
DisableReception waits until current packet receive operation completes.
Allow specifying Tx packet length explicitly.
Fixes DMACopy. Now disables reception during DMA operation (eratta B7.17) and corrects buffer wrap error.
Pauses Reception during GetChecksum (eratta B7.17).
Adds unit tests for checksum and DMA.
GetChecksum - only re-enable reception if already enabled.