Flexible routing

Another massive refactor to change the way routing works. Now any
column can route anywhere.

Also things are generally just much better and more modular via the
new struct split borrowing technique.

I didn't even try to split this into smaller commits for my sanity.

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

src/note.rs

@@ -1,5 +1,5 @@
 use crate::notecache::NoteCache;
-use nostrdb::{Ndb, NoteKey, QueryResult, Transaction};
+use nostrdb::{Ndb, Note, NoteKey, QueryResult, Transaction};
 use std::cmp::Ordering;
 
 #[derive(Debug, Eq, PartialEq, Copy, Clone)]
@@ -13,6 +13,12 @@ impl NoteRef {
         NoteRef { key, created_at }
     }
 
+    pub fn from_note(note: &Note<'_>) -> Self {
+        let created_at = note.created_at();
+        let key = note.key().expect("todo: implement NoteBuf");
+        NoteRef::new(key, created_at)
+    }
+
     pub fn from_query_result(qr: QueryResult<'_>) -> Self {
         NoteRef {
             key: qr.note_key,