Replacing calls to isUartTransmitEmpty with isSoftSerialTransmitBufferEmpty.  Replacing remaing calls to uartWrite with serialWrite.  Adding isSoftSerialTransmitBufferEmpty to the serial API.  Adding serialSet/GetBaudRate to the serial API.  Since softSerial does not implement serialSetBaudRate some GPS serial initialisation code has been updated.

At this point it is probably possible to switch around all the ports and use a software serial implementation if desired.