Reorganize tests and benchmark scripts.

Mainly to get rid of one top level directory. But this will
also be useful when there are tests of the embedding API.

test/language/constructor/default.wren

@@ -0,0 +1,8 @@
+class Foo {
+  toString { "Foo" }
+}
+
+// Classes inherit the argument-less "new" one by default.
+var foo = new Foo
+IO.print(foo is Foo) // expect: true
+IO.print(foo.toString) // expect: Foo

test/language/constructor/infix_class_expression.wren

@@ -0,0 +1,7 @@
+class Foo {
+  +(other) { "Foo " + other }
+}
+
+IO.print(new Foo + "value") // expect: Foo value
+
+// TODO: Other expressions following a constructor, like new Foo.bar("arg").

test/language/constructor/new.wren

@@ -0,0 +1,19 @@
+class Foo {
+  new { IO.print("none") }
+  new() { IO.print("zero") }
+  new(a) { IO.print(a) }
+  new(a, b) { IO.print(a + b) }
+
+  toString { "Foo" }
+}
+
+// Can overload by arity.
+new Foo // expect: none
+new Foo() // expect: zero
+new Foo("one") // expect: one
+new Foo("one", "two") // expect: onetwo
+
+// Returns the new instance.
+var foo = new Foo // expect: none
+IO.print(foo is Foo) // expect: true
+IO.print(foo.toString) // expect: Foo

test/language/constructor/superclass.wren

@@ -0,0 +1,40 @@
+class A {
+  new(arg) {
+    IO.print("new A ", arg)
+    _field = arg
+  }
+
+  aField { _field }
+}
+
+class B is A {
+  new(arg1, arg2) {
+    super(arg2)
+    IO.print("new B ", arg1)
+    _field = arg1
+  }
+
+  bField { _field }
+}
+
+class C is B {
+  new {
+    super("one", "two")
+    IO.print("new C")
+    _field = "c"
+  }
+
+  cField { _field }
+}
+
+var c = new C
+// expect: new A two
+// expect: new B one
+// expect: new C
+IO.print(c is A) // expect: true
+IO.print(c is B) // expect: true
+IO.print(c is C) // expect: true
+
+IO.print(c.aField) // expect: two
+IO.print(c.bField) // expect: one
+IO.print(c.cField) // expect: c