
Display LCD-style digit

This test uses fl_polygon() to draw an LCD digit, using 3 horizontal
and 4 vertical bars. The bar coordinates and dimensions are set in an
array that tells the drawing function how to construct the polygons.
That table is built in a way that allows the display to scale depending
on the value you use for the digit width (dw), and changing the bar
thickness (bw) will work fine as long as you don't go much more than
30% of the digit width. After that it starts to look trippy.
The slider provides a way to see this quickly.

The callback of the number buttons runs through one of 10 tables.
The tables contain an array of 7 numbers, each associated with
one of the 7 bars that make up a digit. If the value of the
current index is 0, the bar is drawn light gray.
Otherwise it is drawn black.


NOTE: There is a bug that causes the button labels to display garbage,
but at this time I don't know the source of this problem.
