Disable intersphinx on windows by default

Revert jupyter_client restriction

i.e. c8e50da3

patch incompatibility between tornado and asyncio

see https://github.com/ipython/ipykernel/pull/480

closes https://github.com/psyplot/psyplot-gui/issues/18

followup of 97fbbe1c

Add preset functionality to GUI

if not TAG is set

marked with expectedFailure

the showTraceback method raises now an error

redesign dataset tree

of a given variable in the ds_tree