Clean up miscellaneous legacy protocol version transitions
Clean up miscellaneous legacy protocol version transitions

This removes some transitional net code for very old versions. As of the
last mandatory release, none of these rules apply.

caraka/gridcoinresearch,theMarix/Gridcoin-Research,gridcoin/Gridcoin-Research,caraka/gridcoinresearch,gridcoin/Gridcoin-Research,Git-Jiro/Gridcoin-Research,Git-Jiro/Gridcoin-Research,gridcoin/Gridcoin-Research,theMarix/Gridcoin-Research,caraka/gridcoinresearch,gridcoin/Gridcoin-Research,theMarix/Gridcoin-Research,caraka/gridcoinresearch,Git-Jiro/Gridcoin-Research,gridcoin/Gridcoin-Research,Git-Jiro/Gridcoin-Research,caraka/gridcoinresearch,Git-Jiro/Gridcoin-Research,theMarix/Gridcoin-Research,gridcoin/Gridcoin-Research,theMarix/Gridcoin-Research,caraka/gridcoinresearch,theMarix/Gridcoin-Research