Vestax VCI-300: Adjust and fine-tune parameters

- Exactly measured the and adjusted jog resolution
  parameters. It's only 1600 instead of 1664 steps per
  revolution!! This was wrong since the initial version :(
- Synchronized jog feedback between scratching and cueing
  by using a linear response
- Slightly increased sensitivity for jog scrolling
- Some code cleanup
Merge pull request #112 from uklotzde/master_Vestax-VCI-300

Vestax VCI-300: Adjust and fine-tune parameters