There are some edge cases to Bresenham's line drawing algorithm with
cumul=dx. The fx-92 SC+ clearly checks cumul>dx, but for dx=1 and dy=1
this results in a horizontal line.
Apparently dx=dy is the only case where the fx-92 SC+ behaves
differently than cumul>dx, as seen with dx=5 dy=4 (causes cumul=dx after
2 iterations but does not trigger the condition).
Also allow the program to be interrupted with Escape while paused.
This change lays the ground for automated unit tests. It adds
command-line options to select the input language format between URL
(hexa text) and plain text, change a few output settings, and redirect
graphical output to an image.
A text lexer has also been added so that unit tests and new programs can
be written in an English-like syntax instead of raw hexadecimal.
Lephe