Tweak IO library a bit:

- Reword some docs.
- Make IO.printAll() public.
- Require () on read.

doc/site/core/io.markdown

@@ -7,38 +7,54 @@ The IO class can be used to read and write to and from the console.
 
 ### IO.**print**(objects...)
 
-Prints any number of things to the console and then prints a newline
-character. If you don't pass it a string, it will be converted to a string for
-you. When passed multiple things, Wren outputs one after another.
+Prints a series of objects to the console followed by a newline. Each object is
+converted to a string by calling `toString` on it. This is overloaded to
+support up to 16 objects. To pass more, use `printAll()`.
 
+  > IO.print("I like bananas")
+  I like bananas
+  > IO.print("Oranges", 10)
+  Oranges10
 
-	> IO.print("I like bananas")
-	I like bananas
-	> IO.print("Oranges", 10)
-	Oranges10
-	>
+### IO.**printAll**(sequence)
+
+Iterates over [sequence] and prints each element, then prints a single newline
+at the end. Each element is converted to a string by calling `toString` on it.
+
+  > IO.printAll([1, [2, 3], 4])
+  1[2, 3]4
 
 ### IO.**write**(object)
 
-Prints a single thing to the console, but does not print a newline character
-afterwards. If you pass it something that isn't a string, it will convert it to
-a string.
+Prints a single value to the console, but does not print a newline character
+afterwards. Converts the value to a string by calling `toString` on it.
 
-	> IO.write(4 + 5)
-	9>
+  > IO.write(4 + 5)
+  9>
 
 In the above example, the result of `4 + 5` is printed, and then the prompt is
 printed on the same line because no newline character was printed afterwards.
 
+### IO.**read**()
+
+Reads in a line of text from stdin. Note that the returned text includes the
+trailing newline.
+
+  > var name = IO.read()
+  John
+  > IO.print("Hello " + name + "!")
+  Hello John
+  !
+  >
+
 ### IO.**read**(prompt)
 
-Reads in and returns a line of text from the console. Takes a single string to
-be used as a prompt. Pass an empty string for no prompt. Note that the returned
-line of text includes the newline character at the end.
+Displays `prompt` then reads in a line of text from stdin. Note that the
+returned text includes the trailing newline.
 
-	> var name = IO.read("Enter your name: ")
-	Enter your name: John
-	> IO.print("Hello " + name + "!")
-	Hello John
-	!
-	>
+  > var name = IO.read("Enter your name: ")
+  Enter your name: John
+  > IO.print("Hello " + name + "!")
+  Hello John
+  !
+  >