pgwidgets-python v0.4.3

Pairs with pgwidgets-js v0.4.3: requires pgwidgets-js >= 0.4.3.

• TreeView / TableView: a column can opt out of the header-click sort.
  A column descriptor can carry "sortable": False to take that column
  out of the header-click sort on an otherwise sortable table. It
  guards against an accidental sort on a column whose values are all
  equal -- the sort leaves nothing on screen to show it happened, and
  the next edit in that column re-sorts the rows and makes the edited
  row jump. The flag gates the user's click only, so sort_by_column()
  still works on an opted-out column. Nothing changed on this side --
  column descriptors go to the browser as given -- but the browser
  honours the flag from pgwidgets-js 0.4.3, which the dependency floor
  now requires.

• TreeView / TableView: the column list is a private copy.
  set_columns(columns) and the columns= constructor option now keep a
  copy of the list they are given, as set_tree() and set_rows() already
  did. insert_column(), append_column() and delete_column() edit the
  stored list in place, and before this they edited the caller's list
  along with it; equally, a caller that kept editing its own list
  changed what a reconnect replayed.