Add a real Pygments lexer for Wren (finally!).

doc/site/control-flow.markdown

@@ -30,14 +30,14 @@ values.
 The simplest branching statement, `if` lets you conditionally skip a chunk of
 code. It looks like this:
 
-    :::dart
+    :::wren
     if (ready) System.print("go!")
 
 That evaluates the parenthesized expression after `if`. If it's true, then the
 statement after the condition is evaluated. Otherwise it is skipped. Instead of
 a statement, you can have a [block](syntax.html#blocks):
 
-    :::dart
+    :::wren
     if (ready) {
       System.print("getSet")
       System.print("go!")
@@ -46,12 +46,12 @@ a statement, you can have a [block](syntax.html#blocks):
 You may also provide an `else` branch. It will be executed if the condition is
 false:
 
-    :::dart
+    :::wren
     if (ready) System.print("go!") else System.print("not ready!")
 
 And, of course, it can take a block too:
 
-    :::dart
+    :::wren
     if (ready) {
       System.print("go!")
     } else {
@@ -67,7 +67,7 @@ they should be familiar if you've used other imperative languages.
 The simplest, a `while` statement executes a chunk of code as long as a
 condition continues to hold. For example:
 
-    :::dart
+    :::wren
     // Hailstone sequence.
     var n = 27
     while (n != 1) {
@@ -87,7 +87,7 @@ The condition for a while loop can be any expression, and must be surrounded by
 parentheses. The body of the loop is usually a curly block but can also be a
 single statement:
 
-    :::dart
+    :::wren
     var n = 27
     while (n != 1) if (n % 2 == 0) n = n / 2 else n = 3 * n + 1
 
@@ -98,7 +98,7 @@ some complex condition. But in most cases, you're looping through a
 [list](lists.html), a series of numbers, or some other "sequence" object.
 That's what `for` is for. It looks like this:
 
-    :::dart
+    :::wren
     for (beatle in ["george", "john", "paul", "ringo"]) {
       System.print(beatle)
     }
@@ -122,7 +122,7 @@ and stop. To do that, you can use a `break` statement. It's just the `break`
 keyword all by itself. That will immediately exit out of the nearest enclosing
 `while` or `for` loop.
 
-    :::dart
+    :::wren
     for (i in [1, 2, 3, 4]) {
       System.print(i)
       if (i == 3) break
@@ -136,7 +136,7 @@ Lists are one common use for `for` loops, but sometimes you want to walk over a
 sequence of numbers, or loop a number of times. For that, you can create a
 [range](values.html#ranges), like so:
 
-    :::dart
+    :::wren
     for (i in 1..100) {
       System.print(i)
     }
@@ -144,7 +144,7 @@ sequence of numbers, or loop a number of times. For that, you can create a
 This loops over the numbers from 1 to 100, including 100 itself. If you want to
 leave off the last value, use three dots instead of two:
 
-    :::dart
+    :::wren
     for (i in 1...100) {
       System.print(i)
     }
@@ -166,14 +166,14 @@ methods on the object that resulted from evaluating the sequence expression.
 
 When you write a loop like this:
 
-    :::dart
+    :::wren
     for (i in 1..100) {
       System.print(i)
     }
 
 Wren sees it something like this:
 
-    :::dart
+    :::wren
     var iter_ = null
     var seq_ = 1..100
     while (iter_ = seq_.iterate(iter_)) {