Kangas

This version includes these changes:
* use /datagrid/query-page instead of /datagrid/query when total is not needed
* use /datagrid/query-total to get total
* someday, use /datagrid/query will be deprecated

This version contains:
* New `datagrid.append_column()` for saved dg's, with computed columns
* New functionality: `kangas server` now runs in parallel
* Expanded the query language to include `x < y < z`
* Added JSON lists (list of JSON items)
* Added VECTORS (lists of numbers)

New in this release:
* Allow regular JSON too (if list of objects)
* Added JSON from cli, eg: `kangas server https://instances.social/instances.json`
* Added ability to read parquet files
* Refactored dg.select() and dg.select_dataframe(), with limit and offset
* Added {"column name"}.split(...)
* Added additional flags: `kangas server huggingface-dataset --streaming --samples N --seed M`

New in this release:
* Show lazy loading spinner, especially for colab images
* Refactored dg.select(), and dg.select_count()
* Added dg.select_dataframe()
* dg.select methods can now take computed_columns
* increased max column length to 10k chars

New in this release:
* Force white background, for now
* List comprehension (see docs) `[PYTHON-EXPRESSION for PYTHON-VAR in SQL-OBJECT if PYTHON-EXPRESSIONS...]`
* Filters from command-line, and dg.show(filter): start kangas up with a filter set
* New examples and documentation

New in this release:
* Updated filter query language:
* added list comprehension to process list data, dicts, and list of dicts
* added any, all, and flatten functions
* will use RestrictedPython, if installed
* added metadata to Image overlay APIs (eg, add_bounding_boxes)
* Protect gethostbyname when on VPN
* Updated checks and docstring for read_csv(header)