Merged VerifyFilename() into OpenFile()
Started moving common data into a single struct,
and writing methods to operate on this struct.
Modified TFTP_Send_Error to use struct Transaction
Modified TFTP_SendAck() to use struct Transaction
Moved error handling into struct Transaction
Moved open file code to main()
Modified code to fork earlier.
This makes the later logic more simple, as if it encounters an error it can simply return.

	modified:   TFTP_Server.c
Changed block counter sizes to be 16 bits
Ran code through astyle
Added code to report transfer rate in Bytes/Second