Port kernels

I've been working on porting kernel generation.   At this point still looking for feedback on the design.  

So far I've ported the Gaussian kernel and the Log kernel from pre-existing sources (knime and trackmate).  Both of these follow the same pattern.  

a) the number of dimensions is defined.
b) the radius (or sigma) is defined as a double 
c) the size of each dimensions in pixels is determined by the radius

I've tried for a class hierchy that will handle these implementations but is flexible as to future variations.