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/lib.rs

@@ -21,13 +21,13 @@ mod key_parsing;
 mod key_storage;
 pub mod login_manager;
 mod macos_key_storage;
+mod nav;
 mod note;
 mod notecache;
 mod post;
 mod profile;
 pub mod relay_pool_manager;
 mod result;
-mod routable_widget_state;
 mod route;
 mod subscriptions;
 mod test_data;
@@ -38,6 +38,7 @@ mod timeline;
 pub mod ui;
 mod unknowns;
 mod user_account;
+mod view_state;
 
 #[cfg(test)]
 #[macro_use]