Big thanks to the 29 contributors who made this release possible.

Here are some highlights ✨:

💄 Add orientation support to the button group (#18762) @SandraMarcelaHerreraArriaga.
💄 Add stacking support to the avatar (#18707) @oliviertassinari.
💄 Add disable elevation support to the button (#18744) @netochaves.
💄 Add size small support to the radio and checkbox (#18688) @SandraMarcelaHerreraArriaga.
🌎 Add 3 new locales (id-Id, ro-RO, nl-NL) @fuadinaqi, @raduchiriac, @JimKoene.
And many more 🐛 bug fixes and 📚 improvements.

[Avatar] Add missing 'fallback' AvatarClassKey (#18717) @kLabz
[ButtonGroup] Add orientation prop (#18762) @SandraMarcelaHerreraArriaga
[Button] disableElevation prop (#18744) @netochaves
[ClickAwayListener] Fix preventDefault logic (#18768) @jayknott
[Container] Add disableGutters prop (#15872) @divyanshutomar
[Drawer] Fix PaperProps className merge conflict (#18740) @siriwatknp
[Modal] Fix scroll jump issue (#18808) @cvara
[Popper] Fix position when changing state or updated (#18813) @Amagon96
[Radio][Checkbox] Add size="small" support (#18688) @SandraMarcelaHerreraArriaga
[Select] Fix incorrect auto-sizing of native select (#18787) @IvanFrescas
[Select] Fix listbox closing on Space keyUp (#18754) @eps1lon
[Table] Add TableContainer component (#18699) @r3dm1ke
[TextField] Fix missing size prop in TypeScript types @sarpt
[TextareaAutosize] Add rowsMin prop (#18804) @lcswillems
[ToggleButton] Add size prop type definition (#18778) @sarfata
[Tooltip] Add popperArrow to TooltipClassKey (#18772) @umidbekkarimov
[Typography] Fix lineHeight for h1-h5 (#18663) @LorenzHenk
[l10n] Add Indonesian (id-Id) locale (#18817) @fuadinaqi
[l10n] Add Romanian (roRO) locale (#18825) @raduchiriac
[l10n] Add dutch translations (#18758) @JimKoene
[useMediaQuery] Support custom window (#18741) @siriwatknp

[AvatarGroup] Introduce new component (#18707) @oliviertassinari
[Autocomplete] Fix double change event issue (#18786) @tplai
[Autocomplete] Add reason to onInputChange callback (#18796) @Tybot204
[Autocomplete] Expand virtualized example to have grouped items (#18763) @Janpot

[blog] November 2019 Update (#18805) @oliviertassinari
[docs] Change readOnly to disabled in text-fields.md example (#18792) @sterjoski
[docs] Fix chip outlined variant (#18806) @scotttrinh
[docs] Improve Avatar fallback description (#18720) @mbrookes
[docs] Improve homepage accessibility (#18745) @mbrookes
[docs] Improve table of contents cmd+click (#18765) @Janpot
[docs] Remove unused dependencies (#18753) @eps1lon
[docs] Revert hiding duplicate link (#18767) @mbrookes
[docs] Simplify MiniDrawer demo (#18814) @shc023