Fixed xxl column prop and added quartz to the theme list (#693)

Author: AnnMarieW

docs/components_page/components/layout.md

@@ -50,7 +50,7 @@ Finally `offset` accepts the integers `1`, ..., `12` and increases the left marg
 
 ## Specify width for different screen sizes
 
-Bootstrap’s grid includes five responsive tiers for building complex responsive layouts. Customize the size, order and offset of your columns on extra small, small, medium, large, or extra large devices using the `xs`, `sm`, `md`, `lg`, and `xl` keyword arguments. Each takes the same arguments as `width` and specifies the column behaviour for that size of screen or larger. `width` secretly just sets `xs`. If you specify both, `xs` will override `width`.
+Bootstrap’s grid includes six responsive tiers for building complex responsive layouts. Customize the size, order and offset of your columns on devices ranging in size from extra small to extra extra large using the `xs`, `sm`, `md`, `lg`, `xl` and `xxl` keyword arguments. Each takes the same arguments as `width` and specifies the column behaviour for that size of screen or larger. `width` secretly just sets `xs`. If you specify both, `xs` will override `width`.
 
 The first of the following two examples has three columns, we set `md=4` indicating that on a 'medium' sized or larger screen each column should take up a third of the width. Since we don't specify behaviour on smaller size screens Bootstrap will allow the rows to wrap so as not to squash the content. You will see this happening if you resize the window you are reading this in.
 

docs/content/docs/themes.md

@@ -115,7 +115,7 @@ The easiest way to link a local stylesheet is to place it in a folder named `ass
 
 There are numerous free to use Bootstrap stylesheets available on the web. The `dash_bootstrap_components.themes` module contains CDN links for Bootstrap and all of the [Bootswatch themes][bootswatch-themes]. Bootstrap also maintains its own [themes website][bootstrap-themes] which lists a number of free and premium themes that you could incorporate into your apps.
 
-To start with, we recommend experimenting with some of the Bootswatch themes available in the `dash_bootstrap_components.themes` module. The full list of available themes is [`CERULEAN`](https://bootswatch.com/cerulean/), [`COSMO`](https://bootswatch.com/cosmo/), [`CYBORG`](https://bootswatch.com/cyborg/), [`DARKLY`](https://bootswatch.com/darkly/), [`FLATLY`](https://bootswatch.com/flatly/), [`JOURNAL`](https://bootswatch.com/journal/), [`LITERA`](https://bootswatch.com/litera/), [`LUMEN`](https://bootswatch.com/lumen/), [`LUX`](https://bootswatch.com/lux/), [`MATERIA`](https://bootswatch.com/materia/), [`MINTY`](https://bootswatch.com/minty/), [`MORPH`](https://bootswatch.com/morph/), [`PULSE`](https://bootswatch.com/pulse/), [`SANDSTONE`](https://bootswatch.com/sandstone/), [`SIMPLEX`](https://bootswatch.com/simplex/), [`SKETCHY`](https://bootswatch.com/sketchy/), [`SLATE`](https://bootswatch.com/slate/), [`SOLAR`](https://bootswatch.com/solar/), [`SPACELAB`](https://bootswatch.com/spacelab/), [`SUPERHERO`](https://bootswatch.com/superhero/), [`UNITED`](https://bootswatch.com/united/), [`VAPOR`](https://bootswatch.com/vapor/), [`YETI`](https://bootswatch.com/yeti/), [`ZEPHYR`](https://bootswatch.com/zephyr/).
+To start with, we recommend experimenting with some of the Bootswatch themes available in the `dash_bootstrap_components.themes` module. The full list of available themes is [`CERULEAN`](https://bootswatch.com/cerulean/), [`COSMO`](https://bootswatch.com/cosmo/), [`CYBORG`](https://bootswatch.com/cyborg/), [`DARKLY`](https://bootswatch.com/darkly/), [`FLATLY`](https://bootswatch.com/flatly/), [`JOURNAL`](https://bootswatch.com/journal/), [`LITERA`](https://bootswatch.com/litera/), [`LUMEN`](https://bootswatch.com/lumen/), [`LUX`](https://bootswatch.com/lux/), [`MATERIA`](https://bootswatch.com/materia/), [`MINTY`](https://bootswatch.com/minty/), [`MORPH`](https://bootswatch.com/morph/), [`PULSE`](https://bootswatch.com/pulse/), [`QUARTZ`](https://bootswatch.com/quartz/), [`SANDSTONE`](https://bootswatch.com/sandstone/), [`SIMPLEX`](https://bootswatch.com/simplex/), [`SKETCHY`](https://bootswatch.com/sketchy/), [`SLATE`](https://bootswatch.com/slate/), [`SOLAR`](https://bootswatch.com/solar/), [`SPACELAB`](https://bootswatch.com/spacelab/), [`SUPERHERO`](https://bootswatch.com/superhero/), [`UNITED`](https://bootswatch.com/united/), [`VAPOR`](https://bootswatch.com/vapor/), [`YETI`](https://bootswatch.com/yeti/), [`ZEPHYR`](https://bootswatch.com/zephyr/).
 
 Check out the [theme explorer](/docs/themes/explorer/) for a live demo of dash-bootstrap-components using all of the different available themes. You may also like to check out the [dash-bootstrap-css](https://github.com/tcbegley/dash-bootstrap-css) project which contains Bootstrap stylesheets that apply consistent styling to various components from dash-core-components.
 

src/components/layout/Col.js

@@ -186,7 +186,7 @@ Col.propTypes = {
    * dictionary with keys 'offset', 'order', 'size'. See the documentation for
    * more details.
    */
-  xl: columnProps,
+  xxl: columnProps,
 
   /**
    * Set vertical alignment of this column's content in the parent row. Options