Start adding eval and machine implementations, remove Inst for now

We're not compiling yet and mostly want to get the name stuff figured
out. Also may switch to using anyhow error handling.

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

src/syn/ast.rs

@@ -1,4 +1,4 @@
-use crate::object::{Float, Int, Str, Value};
+use crate::object::{Float, Int, Str};
 use crate::syn::span::*;
 
 #[derive(Debug, Clone, PartialEq)]