docs: Add support for including markdown files in others.

This uses a third-party dependency, python-markdown-include.

The example use for settings is intended primarily as a demonstration.

requirements/common.txt

@@ -73,6 +73,9 @@ jwt==0.3.2
 # Needed for USING_MANDRILL option for outgoing email
 mandrill==1.0.57
 
+# Needed for including other markdown files for user docs
+markdown-include==0.5.1
+
 # Needed for mock objects in decorators
 mock==2.0.0
 

templates/zerver/help/change-your-language.md

@@ -4,8 +4,7 @@ Zulip is written primarily in English, but it includes feature support for a var
 
 ## Summary:
 
-- Click the gear icon (![Gear Icon](/static/images/help/cog.png)) in the upper right-hand corner of Zulip and select **Settings**.
-    ![Settings Dropdown Menu](/static/images/help/settings-dropdown-menu.png)<br><br>
+- {!settings.md!}
 
 - Scroll down to the **Display Settings**.
 

templates/zerver/help/include/settings.md

@@ -0,0 +1,3 @@
+Click the gear icon (![Gear Icon](/static/images/help/cog.png)) in the
+upper right-hand corner of Zulip and select **Settings**.
+![Settings Dropdown Menu](/static/images/help/settings-dropdown-menu.png)<br><br>

version.py

@@ -1,2 +1,2 @@
 ZULIP_VERSION = "1.4.1+git"
-PROVISION_VERSION = '3.1'
+PROVISION_VERSION = '3.2'

zerver/templatetags/app_filters.py

@@ -10,7 +10,7 @@ import markdown
 import markdown.extensions.admonition
 import markdown.extensions.codehilite
 import markdown.extensions.toc
-
+import markdown_include.include
 
 register = Library()
 
@@ -72,6 +72,7 @@ def render_markdown_path(markdown_file_path):
                 guess_lang=False
             ),
             zerver.lib.bugdown.fenced_code.makeExtension(),
+            markdown_include.include.makeExtension(base_path='templates/zerver/help/include/'),
         ]
     md_engine = markdown.Markdown(extensions=md_extensions)
     md_engine.reset()