ENH: Make more commands scriptable

Source/cmWriteFileCommand.h

@@ -40,6 +40,11 @@ public:
    */
   virtual bool InitialPass(std::vector<std::string> const& args);
 
+  /**
+   * This determines if the command is invoked when in script mode.
+   */
+  virtual bool IsScriptable() { return true; }
+
   /**
    * The name of the command as specified in CMakeList.txt.
    */