Get convex hull at a given threshold

For a given delta lnL, get the convex hull (blob encircling the points) for two dimensions

GetConvexHull(threshold = 2, df, height, x, y)

Arguments

threshold	What value to exclude numbers worse than
df	The data.frame
height	The variable name to use for the height threshold
x	The first variable to look at for the hull
y	The second variable to look at for the hull