Issue 2180 - [cms] Add support for custom Jinja2 functions

README.md

 # CMS #
 
 We use this CMS for [adblockplus.org](https://github.com/adblockplus/web.adblockplus.org/)
 and related websites. It converts a directory with content data into static
 files. You are free to use it for other projects but please keep in mind that we
 make no stability guarantees whatsoever and might change functionality any time.
 
 ## How to use ##
 
 ### Running the test server ###
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 Here `www_directory` should be replaced by the path to your content directory.
 `target_directory` is the path where static files will be placed..
 
 ## Content structure ##
 
 Currently, the following directories of your content directory will be
 considered:
 
 * `filters`: Custom Jinja2 filters
+* `globals`: Custom Jinja2 global functions and variables
 * `includes`: Various include files
 * `locales`: Localization files
 * `pages`: User-visible pages
 * `static`: Static content
 * `templates`: Page layout templates
 
 There should also be a `settings.ini` file with configuration.
 
 All of these are explained in more detail below.
 
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 * Additional variables `head` and `body` are defined with the HTML code that
   should be added to the head and content of the page respectively.
 
 By default, `default.tmpl` will be used for all pages. If other templates are
 defined, the pages need to choose them explicitly using the `template` setting.
 
 ### Custom filters ###
 
 The `filters` directory can define custom Jinja2 filters which will be available
 in all Jinja2 templates. The file name defines the filter name, e.g.
-`myfilter.py` will define a filter named `myfilter`. This file should also
-contain a function called `myfilter`, this one will be called when the filter is
-invoked. For more information on Jinja2 filters see
+`filters/myfilter.py` will define a filter named `myfilter`. This file should
+also contain a function called `myfilter`, this one will be called when the
+filter is invoked. For more information on Jinja2 filters see
 [official documentation](http://jinja.pocoo.org/docs/dev/api/#writing-filters).
+
+### Custom functions and variables ###
+
+The `globals` directory can define custom Jinja2 globals which will be available
+in all Jinja2 templates. Typically, this is used for custom functions. The file
+name should match the name of the function or variable to be defined, and export
+a variable with that name. E.g. `globals/myfunction.py` can define a function
+called `myfunction` that will become available to all Jinja2 templates.