fix selection on focus, fix on the fly property updates

- changing the components props will cause a recalculation and state change
  on the value state. This means if you change the decimal or thousands
  separator on the fly, it will update immediately in the value state,
  instead of when the user makes an input change. Same goes for most other
  properties. (getDerivedStateFromProps)
- improve some comments
- remove some spurious logging
- handleFocus should properly set focus on chrome browsers when focusing
  the field.  (we need to test this with autofocus on too, i think)