Make jinja2 search in user specified directory for templates before

default ford shipped templates

ford/output.py

@@ -45,7 +45,6 @@
 
 loc = pathlib.Path(__file__).parent
 env = jinja2.Environment(
-    loader=jinja2.FileSystemLoader(loc / "templates"),
     trim_blocks=True,
     lstrip_blocks=True,
 )
@@ -120,6 +119,10 @@ def __init__(self, settings: ProjectSettings, proj_docs: str, project, pagetree)
         # Also, in future for other template, we may not need to
         # pass the data obj.
         env.globals["projectData"] = asdict(settings)
+        env.loader=jinja2.FileSystemLoader(
+            settings.html_template_dir + [loc / "templates"]
+        )
+
         self.project = project
         self.settings = settings
         # Jinja2's `if` statement counts `None` as truthy, so to avoid