Restructure node graph project layout

node-graph/gstd/src/main.rs

@@ -0,0 +1,13 @@
+use graphene_core::{Exec, Node};
+use graphene_std::*;
+
+fn main() {
+    let int = value::IntNode::<32>;
+    let _add: u32 = ops::AddNode::<u32>::default().eval((int.exec(), int.exec()));
+    let fnode = generic::FnNode::new(|(a, b): &(i32, i32)| a - b);
+    //let sub = fnode.any(&("a", 2));
+    let cache = memo::CacheNode::new(&fnode);
+    let cached_result = cache.eval(&(2, 3));
+
+    println!("{}", cached_result)
+}