Separated orchid-host and orchid-extension

This is an architectural change that allows me to implment specifics first and generalize along observed symmetries in orchid-base

orchid-base/src/lib.rs

@@ -1,10 +1,9 @@
 pub mod boxed_iter;
-pub mod child;
+pub mod msg;
 pub mod clone;
 pub mod combine;
 pub mod event;
-pub mod expr;
-pub mod gen;
+// pub mod gen;
 pub mod intern;
 pub mod location;
 pub mod name;