The snap-rounding demo maintains and displays three types of objects:

1. Input segments - in black.
2. Segments processed by the snap-rounding procedure - in red.
3. Hot pixels - in green.

You mat insert segments manually (you may want to zoom out or zoom in
before doing this, in order to have a large enough grid to work with).
Alternatively, you can read segments from the input files under the data/
directory, or create input files by yourself.

Each input file should have the following form:

  4
  0.7 0.5   10.7 10.7
  0.7 10.5  10.5 0.5
  10.7 2.5  0.7 2.5
  10.7 7.5  0.7 7.5

That is, the first line specifies the number of segments (call it n),
and is followed by n lines that specify the endpoints of each segment.
An endpoint is given by a pair of real coordinates.
