Error with uint indexes #40

I was getting this error when accessing TIFFStack data using uint32 indexes:

Error using TIFFStack>isvalidsubscript
*** TIFFStack: Subscript indices must either be real positive integers or logicals.

I solved this by changing line 1488 in TIFFStack.m from:
validateattributes(oRefs, {'single', 'double'}, {'integer', 'real', 'positive'});
to:
validateattributes(oRefs, {'numeric'}, {'integer', 'real', 'positive'});

Seems like a logical fix to me, but if I'm not understanding something please let me know.
Let me know if you want me to submit a pull request for this change.

Cheers,
Marcel