Remove Obj and Arena

These weren't being used and they didn't have very good implementations.
Movin' on up

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

src/vm/machine.rs

@@ -67,7 +67,6 @@ pub struct Machine {
     globals: BTreeMap<Word, Value>,
     stack: Vec<Value>,
     max_stack_size: Option<usize>,
-    _arena: Rc<RefCell<Arena>>,
     quote_table: QuoteTable,
     scope_stack: ScopeStack,
     call_stack: Vec<Frame>,
@@ -77,14 +76,12 @@ impl Machine {
     pub fn new(
         globals: BTreeMap<Word, Value>,
         max_stack_size: Option<usize>,
-        arena: Arena,
         scope_stack: ScopeStack,
     ) -> Self {
         Machine {
             globals,
             stack: Default::default(),
             max_stack_size,
-            _arena: Rc::new(RefCell::new(arena)),
             quote_table: Default::default(),
             scope_stack,
             call_stack: Default::default(),
@@ -354,11 +351,6 @@ impl MachineBuilder {
     pub fn finish(mut self) -> Machine {
         self.register_builtins();
 
-        Machine::new(
-            self.globals,
-            self.max_stack_size,
-            Arena::new(self.max_arena_objects),
-            self.scope_stack,
-        )
+        Machine::new(self.globals, self.max_stack_size, self.scope_stack)
     }
 }