reduced 30% time by changing 2d vectors to cv::Mat

[k-okada]

we're using https://github.com/garaemon/SLIC-Superpixels and noticed that @berak's branch was disappeared,
This PR is consists of several his/her contribution of "reduced 30% time by changing 2d vectors to cv::Mat"

This PR is build upon #4

[berak]

hi @k-okada , apologies for removing it (and making it more difficult for you), but i was not quite happy with it at that time (unresolved bugs in the connectivity, inconsistant color handling), also opencv added an own reimplementation of SLIC/O (in opencv_contrib)

but glad to see, you found it useful, and good luck with this !

[k-okada]

On Tue, Aug 30, 2016 at 7:28 PM, berak notifications@github.com wrote:

also opencv added an own reimplementation of SLIC/O (in opencv_contrib)

Oh, I didn't know that, Thanks for info!!!

◉ Kei Okada