rename the pointer read/write methods to read and write

these names were artifacts of some early confusion / bad design i made
in the traits. read and write are much simpler names!

also, change a ptr_mut to ptr where we just read the contents in the
argument marshalling for structs. this has no effect, but it is more
correct.

crates/runtime/src/memory/array.rs

@@ -225,19 +225,19 @@ mod test {
         }
         {
             let ptr = guest_memory.ptr_mut(12).expect("ptr mut to first el");
-            ptr.write_ptr_to_guest(
+            ptr.write(
                 &guest_memory
                     .ptr::<GuestPtr<u8>>(0)
                     .expect("ptr to the first value"),
             );
             let ptr = guest_memory.ptr_mut(16).expect("ptr mut to first el");
-            ptr.write_ptr_to_guest(
+            ptr.write(
                 &guest_memory
                     .ptr::<GuestPtr<u8>>(4)
                     .expect("ptr to the second value"),
             );
             let ptr = guest_memory.ptr_mut(20).expect("ptr mut to first el");
-            ptr.write_ptr_to_guest(
+            ptr.write(
                 &guest_memory
                     .ptr::<GuestPtr<u8>>(8)
                     .expect("ptr to the third value"),

crates/runtime/src/memory/ptr.rs

@@ -80,7 +80,7 @@ impl<'a, T> GuestPtr<'a, T>
 where
     T: GuestTypeClone<'a>,
 {
-    pub fn clone_from_guest(&self) -> Result<T, GuestError> {
+    pub fn read(&self) -> Result<T, GuestError> {
         T::read_from_guest(self)
     }
 }
@@ -210,11 +210,11 @@ impl<'a, T> GuestPtrMut<'a, T>
 where
     T: GuestTypeClone<'a>,
 {
-    pub fn read_ptr_from_guest(&self) -> Result<T, GuestError> {
+    pub fn read(&self) -> Result<T, GuestError> {
         T::read_from_guest(&self.as_immut())
     }
 
-    pub fn write_ptr_to_guest(&self, ptr: &T) {
+    pub fn write(&self, ptr: &T) {
         T::write_to_guest(ptr, &self);
     }
 }