BezierCurve: Fix Build implementation

Now supports multiple segments.
BezierCurve: Log info about 0-order segments in GetPointAt
BezierCurve: +1 anchor makes +1 segment.
BezierCurve: Fix Draw overload
BezierCurve: Fix binary search insert index

Was inserting at wrong index when conquering lower half ended search,
causing AnchorIndices to be unsorted.
BezierCurve: Decrement NumControlPoints in MakeAnchor
BezierCurve: Verbose buffer manipulation logging