Add jinja support to leader_head.content and letter_head.footer (#3493)

* Add jinja support to leader_head.content and letter_head.footer

Add jinja support to leader_head.content and letter_head.footer

* Fix

convert_markdown(doc, meta) was missing my mistake

* Update printview.py

Considering that letter_head could be empty and cleaner code

* Update printview.py

* Update printview.py

* Update printview.py

* Update printview.py

Remove trailing whitespace

frappe/www/printview.py

@@ -136,6 +136,12 @@ def get_html(doc, name=None, print_format=None, meta=None,
 
 	letter_head = frappe._dict(get_letter_head(doc, no_letterhead) or {})
 
+	if letter_head.content:
+		letter_head.content = frappe.utils.jinja.render_template(letter_head.content, {"doc": doc.as_dict()})
+
+	if letter_head.footer:
+		letter_head.footer = frappe.utils.jinja.render_template(letter_head.footer, {"doc": doc.as_dict()})
+
 	convert_markdown(doc, meta)
 
 	args = {