w531t4

Add ability for users to seek/scrub to a new position within song

This capability leans a bit on #41, however it adds on the ability for a user to leverage multiple input device objects. This is relevant for those of us using...

I was implementing this on a RPI, and implementing a rotary encoder is way easier with dtoverlay than with pikeyd. That being said, the dtoverlay implementation doesn't output in KEY_LEFT,...

This branch removes excess trailing spaces, as well as removes whitespace from what are otherwise empty lines.