Add "io" module with beginnings of a File class.

src/cli/modules.c

@@ -3,9 +3,11 @@
 
 #include "modules.h"
 
+#include "io.wren.inc"
 #include "scheduler.wren.inc"
 #include "timer.wren.inc"
 
+#include "io.h"
 #include "scheduler.h"
 #include "timer.h"
 
@@ -30,8 +32,9 @@ typedef struct
 // The array of built-in modules.
 static BuiltInModule modules[] =
 {
+  {"io",        &ioModuleSource,        ioBindForeign,        NULL},
   {"scheduler", &schedulerModuleSource, schedulerBindForeign, NULL},
-  {"timer",     &timerModuleSource, timerBindForeign, NULL},
+  {"timer",     &timerModuleSource,     timerBindForeign,     NULL},
   
   // Sentinel marking the end of the list.
   {NULL, NULL, NULL, NULL}

src/cli/vm.c

@@ -2,8 +2,8 @@
 #include <string.h>
 
 #include "modules.h"
-#include "vm.h"
 #include "scheduler.h"
+#include "vm.h"
 
 #define MAX_LINE_LENGTH 1024 // TODO: Something less arbitrary.