As a user, I can:
● add rows to the grid
● add columns to the grid
● remove rows from the grid
● remove columns from the grid
● select a color from a dropdown menu of colors
● click on a single cell, changing its color to the currently selected color
● fill all uncolored cells with the currently selected color
● fill all cells with the currently selected color
● clear all cells/restore all cells to their original/initial color
● click and hold from a single cell (start) to a different cell (end) such that all affected/hovered-over cells from start to end change to the currently selected color.