tkbio_slider: add app functions to set ticks and pos
- save elem.elem.i in slider.ticks so it can be changed
- add tkbio_slider.h to include with apps
tkbio_slider: event on move
- event on move instead on release
- no event on same tick
- tkbio: all event type functions return tkbio_return
- tkbio: double return for focus out-in
- move verbose to types
add slider application, update readme