presses: Move press handling to Rust

This fixes some rendering things which would happen with multiple state-sharing buttons. It also removes some interfaces exposing rows, views, layouts, and buttons, bringing the code closer to removing them from the FFI entirely.

src/util.rs

@@ -2,6 +2,7 @@
 use std::collections::HashMap;
 use std::rc::Rc;
 
+use std::borrow::Borrow;
 use std::hash::{ Hash, Hasher };
 use std::iter::FromIterator;
 
@@ -111,7 +112,7 @@ pub mod c {
 
         fn clone_owned(&self) -> T {
             let rc = self.clone_ref();
-            let r = rc.borrow();
+            let r = RefCell::borrow(&rc);
             r.to_owned()
         }
     }
@@ -133,7 +134,13 @@ pub fn hash_map_map<K, V, F, K1, V1>(map: HashMap<K, V>, mut f: F)
 }
 
 /// Compares pointers but not internal values of Rc
-pub struct Pointer<T>(Rc<T>);
+pub struct Pointer<T>(pub Rc<T>);
+
+impl<T> Pointer<T> {
+    pub fn new(value: T) -> Self {
+        Pointer(Rc::new(value))
+    }
+}
 
 impl<T> Hash for Pointer<T> {
     fn hash<H: Hasher>(&self, state: &mut H) {
@@ -149,6 +156,18 @@ impl<T> PartialEq for Pointer<T> {
 
 impl<T> Eq for Pointer<T> {}
 
+impl<T> Clone for Pointer<T> {
+    fn clone(&self) -> Self {
+        Pointer(self.0.clone())
+    }
+}
+
+impl<T> Borrow<Rc<T>> for Pointer<T> {
+    fn borrow(&self) -> &Rc<T> {
+        &self.0
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;