Begin deprecating Meta in favor of an ItemId

TODO.md

@@ -1,6 +1,7 @@
 # TODO items
 
 ## General code cleanup
+-experiment with storing metadata via ItemIds on AST nodes (cf. https://rust-lang.github.io/rustc-guide/hir.html, https://github.com/rust-lang/rust/blob/master/src/librustc/hir/mod.rs )
 -implement and test open/use statements
 -implement field access
 - standardize on an error type that isn't String

schala-lang/language/src/ast.rs

@@ -10,16 +10,12 @@ pub use operators::*;
 #[derive(Clone, Debug, PartialEq)]
 pub struct Meta<T> {
   pub n: T,
-  source_map: SourceMap,
-  type_data: TypeData,
   pub fqsn: Option<FullyQualifiedSymbolName>
 }
 
 impl<T> Meta<T> {
   pub fn new(n: T) -> Meta<T> {
     Meta { n,
-    source_map: SourceMap::default(),
-    type_data: TypeData::new(),
     fqsn: None,
     }
   }