Fixes vega#2622

* Change to sphinx pydata theme

* Update templates, css, and config for the pydata theme

* Update index structure for the pydata theme

* Move case studies and setup redirect

* Point to Vega-Lite docs for mark properties

* Add headings and reorganize order of sections and headings for clarity

* Remove ToC dropdown error created from empty ToC

* Improve ToC for galleries and move seattle weather to original location

* Do not use rediraffe since it is now not needed

Also move a couple of section inside conf.py

* Rename API Reference topbar entry

* Move the `...` button next to each chart

* Add getting help landing page

* Format to pass flake8 tests

* Make gallery and mini-gallery paths relative so that images show up

* Compute current copyright year

* Use recommend way to install via pip

Remove dollar sign for easy copy paste

* Adjust title positioning for narrow screens/windows

* Remove use of deprecated functionality from the documentation

* Merge interactions 1 and 2

* Contrast variable and selection parameters in expression strings

* Note how to use custom Panel callbacks with Altair selections

* Add more succinct example of selecting columns from dropdowns

* Make examples equivalent

* Pin selenium to avoid breakage from deprecation

* Switch to double quotes

…tion

Remove broken Wikipedia donations chart

Tidy Falkensee case study

Tidy up U.S. Population by Age and Sex case study

Move bar chart with highlighted segment chart into the bar charts section

No need to say "Example" in the example headline

Isotype charts aren't case studies and should go in the other category

Top k charts aren't case studies and should go with other charts

Add pyramid pie chart to case studies

Move image tooltip example to interactive charts section

Move window rank technique to line charts section

Style fix to chart headline

Move scatter with histogram into scatter plots section

Clean up airport maps

Example of a line chart with a label annotating the final value

Update ranged_dot_plot.py

Co-authored-by: Mattijn van Hoek <[email protected]>

Co-authored-by: Mattijn van Hoek <[email protected]>

Co-authored-by: Mattijn van Hoek <[email protected]>

Co-authored-by: Mattijn van Hoek <[email protected]>

Co-authored-by: Mattijn van Hoek <[email protected]>

Co-authored-by: Mattijn van Hoek <[email protected]>

Co-authored-by: Mattijn van Hoek <[email protected]>

* Create a new heatmaps section

* Update layered_heatmap_text.py

* Update altairgallery.py

* Update hexbins.py

* Update binned_heatmap.py

* Update hexbins.py

* Update altairgallery.py

* Update table_bubble_plot_github.py

* Update wind_vector_map.py

* Update layered_heatmap_text.py

…ga#2640)

* Delete multiple_marks.py

* Create line_chart_with_points_different_color.py

* Update line_chart_with_points.py

* Rename line_chart_with_points_different_color.py to line_chart_with_points_stroked.py

* docs: Fix a few typos

There are small typos in:
- altair/sphinxext/altairplot.py
- altair/sphinxext/schematable.py
- altair/utils/tests/test_mimebundle.py
- doc/user_guide/display_frontends.rst

Fixes:
- Should read `required` rather than `requred`.
- Should read `temporary` rather than `temporay`.
- Should read `aspects` rather than `spects`.
- Should read `render` rather than `rendeer`.

* Fix typos

Co-authored-by: Joel Ostblom <[email protected]>

…ga#2647)

* Move parallel coordinates to line charts section

* Update normed_parallel_coordinates.py

* Update line_chart_with_points.py

* Move other charts into new advanced calculations section

* Big C

* Add back other charts

Co-authored-by: Joel Ostblom <[email protected]>

* Add line chart with interpolation

* Switch line chart to points to use wheat data

* Add stroked points

* Tidy multi series line chart

* Update multi_series_line.py

* Update multi_series_line.py

* Update line_chart_with_interpolation.py

* Delete line_chart_with_stroked_points.py

* Update examples and tests to VL5 syntax

* Fix typo

* added argmax example

* Update line_chart_with_custom_legend.py

Fixed y axis labeling

* Apply suggestions from code review

Co-authored-by: Joel Ostblom <[email protected]>

* Update code formatting

Co-authored-by: Joel Ostblom <[email protected]>

minor: update readme code