imgproc: Morphology erode and dilate

Hi,

I have added two morphology functions based on a partial Open CV port to Javascript located here:
http://code.google.com/p/js-handtracking/

I have allowed in place modifications of data_t by allocating a temporary array buffer copied from the source using the ArrayBuffer.slice method. 

You may want to change that to use a matrix_t/data_t 'slice' method that would hide the fact that ArrayBuffer.slice is not supported in IE. 

Cheers

David