Add lists

This introduces:

* new syntax for list literals, put comma-separated values between
  braces for your new list
* new syntax for indexing, do `foo[index]` to get the value in `foo` at
  `index`. Lists also allow negative indices too. Any type that wants to
  be indexed can include their own __index__ function as well.
* new VM instruction, BuildList. List literals were a lot easier to
  implement using this rather than creating a new list, creating a
  temporary stack value, and then duplicating + pushing to that
  temporary value over and over.

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

src/obj/ty.rs

@@ -184,6 +184,21 @@ pub fn init_types() {
         Obj {
             //__call__ => BuiltinFunction::create("__call__",
         },
+        List {
+            // Conversion methods
+            to_repr => BuiltinFunction::create("to_repr", List::to_repr, 1),
+
+            // Constructor
+            __call__ => BuiltinFunction::create("__call__", List::do_call, 2),
+            __init__ => BuiltinFunction::create("__init__", List::init, 2),
+
+            // Operators
+            __index__ => BuiltinFunction::create("__index__", List::index, 2),
+
+            // Methods
+            push => BuiltinFunction::create("push", List::push, 2),
+            pop => BuiltinFunction::create("pop", List::pop, 1),
+        },
         Str {
             // Conversion methods
             to_str => BuiltinFunction::create("to_str", Str::to_str, 1),
@@ -198,7 +213,9 @@ pub fn init_types() {
             // Operators
             __add__ => BuiltinFunction::create("__add__", Str::add, 2),
             __mul__ => BuiltinFunction::create("__mul__", Str::mul, 2),
-            // .lower, .upper, .slice, etc
+
+            // Methods
+            // TODO Str methods - .lower, .upper, .slice, etc
         },
         Int {
             // Conversion methods