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/while/closure_in_body.wren

@@ -0,0 +1,13 @@
+var list = []
+
+var i = 1
+while (i < 4) {
+  var j = i + 1
+  list.add(new Fn { IO.print(j) })
+  i = i + 1
+}
+
+for (f in list) f.call()
+// expect: 2
+// expect: 3
+// expect: 4

test/language/while/newline_after_while.wren

@@ -0,0 +1,2 @@
+while // expect error
+(true) IO.print("bad")

test/language/while/return_closure.wren

@@ -0,0 +1,10 @@
+var f = new Fn {
+  while (true) {
+    var i = "i"
+    return new Fn { IO.print(i) }
+  }
+}
+
+var g = f.call()
+g.call()
+// expect: i

test/language/while/return_inside.wren

@@ -0,0 +1,9 @@
+var f = new Fn {
+  while (true) {
+    var i = "i"
+    return i
+  }
+}
+
+IO.print(f.call())
+// expect: i

test/language/while/syntax.wren

@@ -0,0 +1,16 @@
+// Single-expression body.
+var c = 0
+while (c < 3) IO.print(c = c + 1)
+// expect: 1
+// expect: 2
+// expect: 3
+
+// Block body.
+var a = 0
+while (a < 3) {
+  IO.print(a)
+  a = a + 1
+}
+// expect: 0
+// expect: 1
+// expect: 2

test/language/while/truth.wren

@@ -0,0 +1,26 @@
+// False and null are false.
+while (false) {
+  IO.print("bad")
+  break
+}
+
+while (null) {
+  IO.print("bad")
+  break
+}
+
+// Everything else is true.
+while (true) {
+  IO.print("true") // expect: true
+  break
+}
+
+while (0) {
+  IO.print(0) // expect: 0
+  break
+}
+
+while ("") {
+  IO.print("string") // expect: string
+  break
+}