Make the property “Display Candidates/Hide Candidates” actually work

- There is no set_candidates_list_visible() in ibus 1.5.5.
  use hide_lookup_table() instead to hide the candidates if requested
- also hide the auxiliary text if hiding of the candidates is requested
- make changing of that property by changing the gconf key work
  (name == u'AlwaysShowLookup' won’t work it needs to be all lower case)
- There was a typo here: “self._new_property(u'always_show_loopup')”
  (“lookup”, not “loopup”)
- The property menus show the current state, not the state which will
  be switched to when the menu entry is pressed. For example,
  one property says “Half-width punctuation” when half-width punctuation
  is in use, clicking it switches to full-width punctuation and
  then the menu displays “Full-width punctuation”. The property menu
  for displaying and hiding candidates did that reversed. Make it
  behave like the other property menus do.