Link identification

When this is on, then two or more XGobis that were initiated
with the same data (or have the same number of rows) are
linked for identification.  That is, if one XGobi is in 
Identify, any case labelled in that XGobi's plotting window
are promptly labelled in the other XGobis.

This is most frequently used when the XGobi plotting windows
display different views of the same data.

Note:  For computational efficiency, the receiving XGobis
should be in XYPlot, DotPlot, or paused in Rotate or Tour.

This can be set in the XGobi resource file.  The default is

*linkIdentify:   True

