Tying inheritance instead of templating.

Templating was requiring us to write lots of duplicate code
to handle each type we cared about, which seems cross-purposes.
I have migrated the code to use inheritance instead in hopes
of simplifying the task of adding new supported types.
fixed chaining.

Also cleaned up some of the TweenManager code.
Modified how and when start and end times are calculated.
fixed delay/duration/start/end mixup.
added git ignore
added some stuff to the example
Merge branch 'pr/2'
Merge branch 'master' of https://github.com/Larsberg/Tweener