Add mask parameter to matrix.matchTemplate

[acinader]

Add examples for matchTemplate with and without mask.

Due to #381 I forked this off of v5.0.0 commit 5fb426aa1428b3d16e7fb0b1412f44410077382e which is why it has conflicts.

I'm glad to rebase it when #381 is resolved and head can do a templateMatch without an assert fail.

In matrix.cpp, I don't check if the opencv version can handle the mask (>= 3.1 it think?). I poked around a little to see if this is done anywhere, but didn't see. Let me know if its important and I can poke around some more to find an example.

[acinader]

@pkallos, is that less ambiguous? Glad to take out too....

[acinader]

I now also see that this conflicts (not irresolvably :)) with #389

So i need some direction on how to integrate that mask functionality. You can see my suggestion in https://github.com/peterbraden/node-opencv/pull/389#issuecomment-227258155

I'd like to help out and get the match with a mask into the main line.

[pkallos]

One solution is to follow my suggestion in #403 and partially revert #389, basically revert everything except for the cv::imread(filename, -1);

[peterbraden]

I merged #428 which I think partially addresses this, but I'm not sure what the best api looks like for this, and I haven't used any of these functions. Also interested in #403 - what do you all think an api should look like?