increased accuracy at the expense of timing- 91.3%

the previous way didn’t write all of the lines (see input80.txt)
because it only determined whether a line would be shown by whether or
not its starting point had already been covered (the problem is when
some lines depart from the same starting point; those did not show).
ideally no checks for repeated lines would have to take place but we
don’t want subsegments either… this latest commit increases the
accuracy (though not to 100% yet) but adds a significant time lag which
fails 1 out of the 17 tests