added language (a config value) and character set to default template

doc/configuration.toml

@@ -56,6 +56,8 @@ stylesheet = "dragonglass.css"
 [metadata]
 # If true, use page title as default description.
 description-title = false
+# The language of the site, expressed as a RFC5646 language identifier.
+lang = "en"
 # The site base URL. If supplied, this will be added to a <base> element in the page metadata.
 sitebase = ""
 # The site title. If supplied, this will be included in page metadata and used to formulate the default title.

doc/template-vars.txt

@@ -1,20 +1,23 @@
 TEMPLATE VARIABLES PROVIDED BY DRAGONGLASS WHEN RENDERING A DOCUMENT
 
-backlinks
+backlinks:
     A list of pages that link to the page being rendered. Formatted as a list of dicts with
     two elements, "name" and "link", containing the page title and the link to it, respectively.
 
-default_stylesheet
+default_stylesheet:
     The filename of the default stylesheet which is generated by dragonglass and added to the
     generated pages.
 
-description
+description:
     The description of this page. May be empty.
 
-dragonglass_version
+dragonglass_version:
     The version number of dragonglass.
 
-python_version
+lang:
+    The configured site language, as a RFC5646 language identifier.
+
+python_version:
     The version number of Python that's running dragonglass.
 
 site_base:
@@ -26,8 +29,8 @@ site_title:
 tags:
     A list of all tags the page being rendered has, in sorted order.
 
-text
+text:
     The text of the page being rendered.
 
-title
+title:
     The title of the page being rendered.