Added convexHull()

[VictorKubrak]

Description of new feature

• convexHull() receives array of points with (x,y) coordinates
• returns smallest sorted array of points that belong to smallest convex hull of received points
• sorted array means that array[i] and array[i+1] are adjacent vertices of a hull (array[0] and array[array.length-1] are also adjacent)

Checklist

• Your branch is up-to-date with the base branch
• You've included at least one test if this is a new feature
• All tests are passing

People to notify

@manrajgrover