Began implementing fully isomorphic macros

Like Rust's Proc macros. Now we have preprocessor recursion to worry about. I also made a cool macro for enums

orchid-host/src/macros.rs

@@ -0,0 +1,20 @@
+use std::sync::RwLock;
+
+use hashbrown::HashMap;
+use lazy_static::lazy_static;
+use orchid_base::macros::MTree;
+use trait_set::trait_set;
+use crate::api::ParsId;
+
+trait_set!{
+  trait MacroCB = Fn(Vec<MTree>) -> Option<Vec<MTree>> + Send + Sync;
+}
+
+lazy_static!{
+  static ref RECURSION: RwLock<HashMap<ParsId, Box<dyn MacroCB>>> = RwLock::default();
+}
+
+pub fn macro_recur(run_id: ParsId, input: Vec<MTree>) -> Option<Vec<MTree>> {
+  (RECURSION.read().unwrap()[&run_id])(input)
+}
+