1.7 - tempo slider + dynamic fileview

Tempo Slider officially working. There is an unavoidable issue where the
Timer must be stopped before a tempo change will take place, but the
slider takes care of that for us so it will work regardless of whether
the user has is paused or playing, the sound will just stop until they
stop sliding.

Files now disappear/appear upon deletion and save.

Be sure to read over my last commit.