Edit blogs, and add blog icons and banners (#460)

Also adds a parameter to `md_to_html` to only render inline elements (so that we don't have titles or images in blog descriptions). And moves the delete button for the blog on the edition page.

I still have to update the SQLite migration once others PRs with migrations will be merged.

Also, there will be a problem when you edit a blog while not owning its banner or icon: when validating they will be reset to their default values… I don't see a good solution to this until we have a better way to handle uploads with Rocket (the same is probably happening for articles btw).

And the icon/banner are not federated yet, I don't know if I should add it to this PR or if it can come after?

![image](https://user-images.githubusercontent.com/16254623/53894510-7d853300-4030-11e9-8a2c-f5c0b0c7f512.png)
![image](https://user-images.githubusercontent.com/16254623/53894539-8b3ab880-4030-11e9-8113-685a27be8d7c.png)

Fixes #453
Fixes #454

plume-common/src/utils.rs

@@ -46,8 +46,22 @@ enum State {
     Ready,
 }
 
+fn to_inline(tag: Tag) -> Tag {
+    match tag {
+        Tag::Header(_) | Tag::Table(_) | Tag::TableHead | Tag::TableRow | Tag::TableCell => {
+            Tag::Paragraph
+        }
+        Tag::Image(url, title) => Tag::Link(url, title),
+        t => t,
+    }
+}
+
 /// Returns (HTML, mentions, hashtags)
-pub fn md_to_html(md: &str, base_url: &str) -> (String, HashSet<String>, HashSet<String>) {
+pub fn md_to_html(
+    md: &str,
+    base_url: &str,
+    inline: bool,
+) -> (String, HashSet<String>, HashSet<String>) {
     let parser = Parser::new_ext(md, Options::all());
 
     let (parser, mentions, hashtags): (Vec<Event>, Vec<String>, Vec<String>) = parser
@@ -69,6 +83,26 @@ pub fn md_to_html(md: &str, base_url: &str) -> (String, HashSet<String>, HashSet
             Some(res)
         })
         .flat_map(|v| v.into_iter())
+        // Ignore headings, images, and tables if inline = true
+        .scan(vec![], |state: &mut Vec<Tag>, evt| {
+            if inline {
+                let new_evt = match evt {
+                    Event::Start(t) => {
+                        let tag = to_inline(t);
+                        state.push(tag.clone());
+                        Event::Start(tag)
+                    }
+                    Event::End(t) => match state.pop() {
+                        Some(other) => Event::End(other),
+                        None => Event::End(t),
+                    },
+                    e => e,
+                };
+                Some(new_evt)
+            } else {
+                Some(evt)
+            }
+        })
         .map(|evt| match evt {
             Event::Text(txt) => {
                 let (evts, _, _, _, new_mentions, new_hashtags) = txt.chars().fold(
@@ -239,7 +273,7 @@ mod tests {
 
         for (md, mentions) in tests {
             assert_eq!(
-                md_to_html(md, "").1,
+                md_to_html(md, "", false).1,
                 mentions
                     .into_iter()
                     .map(|s| s.to_string())
@@ -264,7 +298,7 @@ mod tests {
 
         for (md, mentions) in tests {
             assert_eq!(
-                md_to_html(md, "").2,
+                md_to_html(md, "", false).2,
                 mentions
                     .into_iter()
                     .map(|s| s.to_string())
@@ -272,4 +306,16 @@ mod tests {
             );
         }
     }
+
+    #[test]
+    fn test_inline() {
+        assert_eq!(
+            md_to_html("# Hello", "", false).0,
+            String::from("<h1>Hello</h1>\n")
+        );
+        assert_eq!(
+            md_to_html("# Hello", "", true).0,
+            String::from("<p>Hello</p>\n")
+        );
+    }
 }