*MEX* Modified Hausdorff Distance for 2D Point Sets

This function computes the Modified Hausdorff Distance (MHD) which is
proven to function better than the directed HD as per Dubuisson et al.
in the following work:

M. P. Dubuisson and A. K. Jain. A Modified Hausdorff distance for object
matching. In ICPR94, pages A:566-568, Jerusalem, Israel, 1994.
http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=576361

The function computed the forward and reverse distances and outputs the
minimum of both.

Format for calling function:

MHD = ModHausdorffDist(A,B);

where
MHD = Modified Hausdorff Distance.
A -> Point set 1
B -> Point set 2

No. of samples of each point set may be different but the dimension of
the points must be the same (2).