Generalize python ts flags and colors set/get foo

Generalize python ts flags and colors set/get foo
- make flags, vsflags, color, prefcolor (previously not available)
  and probFilter appear as internal attributes of ts objects, each
  with their own setter/getter methods
- make the old custom set/get methods access the internal attributes instead
- keeping them "internal only" leaves room for adding further sanity
  checking and nicer interface on python side while giving direct access
  bits for those who want it
- not deprecating the old get/set methods at least yet...