Returns character vector of rownames of the selected points from data if
names parameter is TRUE. If names is FALSE then a logical vector indicating whether points
are in the polygon is returned.
Details
Freehand select function. First generate a 2D plot using R's plot function,
then select gate region by left clicking. Close polygon by right clicking.
The function will return the rownames of the enclosed points by the rownames
of th co-ordinates given in data.