Theming (#624)

* Theming

- Custom CSS for blogs
- Custom themes for instance
- New dark theme
- UI to choose your instance theme
- Option to disable blog themes if you prefer to only have the instance theme
- UI to choose a blog theme

src/routes/blogs.rs

@@ -181,6 +181,7 @@ pub struct EditForm {
     pub summary: String,
     pub icon: Option<i32>,
     pub banner: Option<i32>,
+    pub theme: Option<String>,
 }
 
 #[get("/~/<name>/edit")]
@@ -207,6 +208,7 @@ pub fn edit(name: String, rockets: PlumeRocket) -> Result<Ructe, ErrorPage> {
                 summary: blog.summary.clone(),
                 icon: blog.icon_id,
                 banner: blog.banner_id,
+                theme: blog.theme.clone(),
             },
             ValidationErrors::default()
         )))
@@ -318,6 +320,7 @@ pub fn update(
             );
             blog.icon_id = form.icon;
             blog.banner_id = form.banner;
+            blog.theme = form.theme.clone();
             blog.save_changes::<Blog>(&*conn)
                 .expect("Couldn't save blog changes");
             Ok(Flash::success(