CPU (non-OpenCL) CLAHE Support for CV_16UC1 Images

The CPU implementation (non-OpenCL) implementation algorithm now supports image types of any OpenCV supported integer types.  Addresses: CLAHE Lacks Support for Other Image Types (Feature #3749).
yes, this is a bit weird. Change "Mat&" parameters in loop body constructors to "const Mat&" and it compiles. BTW, I also found another problem. If you use 4096 bins, the sift needs to be set to 4, not 6