Initial implementation if ugc, see #16; Fix tests

tests/compiler/export.ts

@@ -6,14 +6,23 @@ function sub(a: i32, b: i32): i32 {
   return a - b;
 }
 
-export { sub as renamed_sub };
+export { sub };
+
+function mul(a: i32, b: i32): i32 { // not exported as "mul"
+  return a * b;
+}
+
+export { mul as renamed_mul };
 
 export const a: i32 = 1;
 
 const b: i32 = 2;
-b;
 
-export { b as renamed_b };
+export { b };
+
+const c: i32 = 3; // not exported as "c"
+
+export { c as renamed_c };
 
 export namespace ns {
   function one(): void {}