AMIDST excel: Add `WltpRunner.xlsm` UI based on xlwings lib.

* json: BUG discovered in set jsonpointer overwritting intermediates (TC added but not fixed).
* tkui: Detect and raise if run under python-2
* build: Add xlwings dependency.
* build: Resotre eclipse python-source from 2.7-->3.0.
[ci skip]
excel: Add `WltpRunner.xlsm` UI based on xlwings lib.

* pandel,json: FIX `set_jsonpointer()`.
excel: Finalize excel UI based on xlwings lib.

* excel: Add cmdline --excel option.
** Move python-code from excel-->python file.
** possible to debug xlwings-python code from cmdline.
** Shrink excel-file.
** docs improvements.
* utils: Add filename generator.
* ci: Attempt to fix build-failure with Pillow(?) with apt-get p3-tk.