Continued Work: FilmStripSelector

Indicators for changing the selected item now change color based on
whether or not the selected index can be increased and/or decreased.
Continued Work: FilmStripSelector

Set it up so that the selected index is always drawn while clipping the
number of drawn items down to the number that fits in the drawing area
(width wise) that is given.
Continued Work: FilmStripSelector

Pulled some of the code out from the Draw method. I also shifted the
right side indicator that that it is the same distance from the last
drawn item as the left indicator is from the first drawn item.