[613] Use server timezone in timestamp conversion
Detail: The SMB protocol requires the timesstamp to be in the server's timezone. The serverTimeZone returned by SMB_Negotiate is used to convert the RISC OS timestamp to SMB timestamp.
Fixes Ticket #613
Modifief files: Corefn.c SMB.c Xlate.c SMB.h Xlate.h
Tests: Tested by reading the filestamp of a saved file on Windows, Linux and RISC OS.
Tested with AMU. Compiling from a linux
server AMU now sees mods to files made from
other OS as newer.
Note: Connecting to a local server in the winter in the UK will not show the timestamp problem as the server timezone will be 0.