remove treehouse-format crate and collapse everything into src

src/html.rs

@@ -0,0 +1,40 @@
+use std::fmt::{self, Display, Write};
+
+pub mod breadcrumbs;
+pub mod djot;
+pub mod highlight;
+pub mod navmap;
+pub mod tree;
+
+pub struct EscapeAttribute<'a>(pub &'a str);
+
+impl Display for EscapeAttribute<'_> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        for c in self.0.chars() {
+            if c == '"' {
+                f.write_str("&quot;")?;
+            } else {
+                f.write_char(c)?;
+            }
+        }
+        Ok(())
+    }
+}
+
+pub struct EscapeHtml<'a>(pub &'a str);
+
+impl Display for EscapeHtml<'_> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        for c in self.0.chars() {
+            match c {
+                '<' => f.write_str("&lt;")?,
+                '>' => f.write_str("&gt;")?,
+                '&' => f.write_str("&amp;")?,
+                '\'' => f.write_str("&apos;")?,
+                '"' => f.write_str("&quot;")?,
+                _ => f.write_char(c)?,
+            }
+        }
+        Ok(())
+    }
+}