Rewrote code algorithm for twilight and day/mode

Rewrote code algorithm for twilight and day/mode to eliminate using file
trigger points based on maximum file sizes.  I now use the current file
sizes to look for mode switches and set an absolute range to trigger
twilight mode.  (needs more testing).  Otherwise it works a lot better
then previous code.  Apologies if this cause any grieve to those that
might have cloned this project.
See Readme description for code changes

My apologies to anyone who cloned the previous version.  It did not work
as well as expected under more testing.  This version has more
simplified logic and uses a better algorithm.  I am still doing more
testing but initial code looks OK so far.