* 12to11.c (DetermineServerTime): Correctly handle server time
truncation.
* Imakefile (SRCS): Add time.c
(OBJS): Add time.o.
* compositor.h (struct _Timestamp, enum _TimestampDifference):
New structure and enum.
(TimestampIs, TimeIs): New macros.
(struct _CreateOfferFuncs): Accept Timestamp, not Time.
* data_device.c (UpdateSingleReferenceWithForeignOffer)
(XLSetForeignSelection, XLClearForeignSelection): Accept
Timestamp, not Time.
* dnd.c (XLDoDragMotion):
* picture_renderer.c (InitRenderFuncs):
* primary_selection.c (UpdateSingleReferenceWithForeignOffer)
(XLSetForeignPrimary, XLClearForeignPrimary): Adjust for changed
timestamp handling.
* seat.c (struct _Seat): New field `last_user_time'.
(HandleRawKey, DispatchMotion): Record last user time as
timestamp.
(GetLastUserTime, XLSeatGetLastUserTime): Return Timestamp, not
Time.
* select.c (FindWriteTransfer, TransferFinished)
(TransferBecameReadable, ConvertSelectionMultiple)
(HandleSelectionRequest, DrainQueuedTransfers)
(HandlePropertyDelete, HandlePropertyNotify): Allow duplicate
write transfers if the other is only waiting for property
deletion.
* xdata.c (ReceiveBody, HandleOfferResourceDestroy)
(AllocateTimestamp, CreateOffer, CreatePrimaryOffer, SendOffers)
(SendPrimaryOffers, HandleNewSelection, NoticeClipboardCleared)
(NoticePrimaryCleared, HandleSelectionNotify)
(XLNoteSourceDestroyed, NoteLocalSelectionBody)
(NoteLocalSelectionFooter): Adjust timestamp handling to use
wraparound-safe Timestamp and not Time.
