#1941, 1948 - Fix possible warnings in movie and graphics helpers, add functions to convert between seconds and hh:mm:ss.dd.
Also add unit tests for new movie helper functions.
Merge pull request #88 from shadlaws/fix_1941

#1941, 1948 - Fix possible warnings in movie and graphics helpers, add functions to convert between seconds and hh:mm:ss.dd (and their unit tests).