Light Up
========

You have to place lightbulbs in the grey squares to 
light up every free space without breaking the rules.

A number in a square means that it is adjacent to only 
that number of lightbulbs (diagonals don't count).

No lightbulb can "light" another lightbulb by being
in the same row or column.  All free squares must be
lit.

A-click to place a lightbulb.
B-click to place a "no lightbulb" marker.
