GLCMFeatures(glcm)

Vectorized GLCM Texture features calculations

This code is a vectorized AND CORRECTED version of the code submitted by Avinash Uppuluri.
The speedup is around 20x - 100x depending on GLCM size, and about 4x speedup of Avinash Uppuluri's own vectorized version.
N.B. "Sum of square: variance", "sum variance" and "difference variance" are not correctly implemented in Avinash Uppuluri's code! I have updated these.

I have also changed the nomenclature to make things more clear:
I use the term "Inverse difference" instead of "homogeneity in matlab" or "homom".
I use the term "Homogeneity" instead of "Inverse difference moment" or "homop".

I have commented out "inverse difference normalized" and "inverse difference moment normalized", since I do not see the point of only normalizing these features. (If you want these features for continuity you can remove the comments in this code to use them)