Rewrite note parsing in C

This eliminates any parsing choppyness

Fixes: #32
Signed-off-by: William Casarin <jb55@jb55.com>

damus/Views/NoteContentView.swift

@@ -32,7 +32,7 @@ func render_note_content(ev: NostrEvent, profiles: Profiles, privkey: String?) -
 
 func is_image_url(_ url: URL) -> Bool {
     let str = url.lastPathComponent
-    return str.hasSuffix("png") || str.hasSuffix("jpg") || str.hasSuffix("jpeg")
+    return str.hasSuffix("png") || str.hasSuffix("jpg") || str.hasSuffix("jpeg") || str.hasSuffix("gif")
 }
 
 struct NoteContentView: View {