Confusion between x|c and y|r in documentation

[judu]

The grid's documentation reads: "cells: a matrix representing the coordinates of this grid. Cells are indexed as [row][column]". Where row is y and column is x. But in the code, cells are actually indexed as [column][row](tested in 1.2.2). I would advise the use of either [x][y] or [column][row] everywhere te be clear.

[sbiermanlytle]

The documentation is wrong, it will be corrected for 1.3.