Package matrix implements iterator for matrix navigation

§ Quick start

Use this package to minimize complexity when navigatin 2D matrix
structures.  To loop over an matrix from top, left corner to bottom,
right

	for nav, x, y, inside := NewNavigator(3, 3); inside; x, y, inside = nav.Right() {
		// do something
	}

Note that all navigation methods wrap at the edge of the given boundary.

	  0 1 2 3 4
	-+---------+
	0| | | | | |
	1| |-|-|-| |
	2| |-|>|x| |
	3| |x|x|x| |
	4| | | | | |
	-+---------+