theme: upgrade to latest v4.1 dev (talk front matter upgraded)

Also:

- Project and Custom widgets renamed (upgraded)
- Rearranges section positions and adds demo section to introduce
the template and help the user get started

config/_default/menus.toml

@@ -6,36 +6,36 @@
 [[main]]
   name = "Home"
   url = "#about"
-  weight = 1
-
-[[main]]
-  name = "Publications"
-  url = "#publications_featured"
-  weight = 2
+  weight = 10
 
 [[main]]
   name = "Posts"
   url = "#posts"
-  weight = 3
+  weight = 20
 
 [[main]]
   name = "Projects"
   url = "#projects"
-  weight = 4
+  weight = 30
+
+[[main]]
+  name = "Publications"
+  url = "#featured"
+  weight = 40
 
 [[main]]
   name = "Tutorials"
   url = "/tutorial/"
-  weight = 5
+  weight = 50
 
 [[main]]
   name = "Contact"
   url = "#contact"
-  weight = 6
+  weight = 60
 
 # Link to a PDF of your resume/CV from the menu.
 # To enable, copy your resume/CV to `static/files/cv.pdf` and uncomment the lines below.
 # [[main]]
 #    name = "CV"
 #    url = "files/cv.pdf"
-#    weight = 7
+#    weight = 70