No more pandas

[TheChymera]

PR to track removing pandas, as described here.

The way this works is that:

• Pandas-using functions are duplicated (e.g. make_entity_table() duplicated as _make_entity_table()) and pandas usage is incrementally reduced.
• For each duplicated function the test suite includes a test of the form test_make_entity_table_transition() which returns an attempt at a prettified diff if the outputs of the two functions do not match.
• The test can be run as pytest tests/test_render.py::test_make_entity_table_transition