Work on if, call and system tags.

__call.h

@@ -1,14 +1,14 @@
-#ifndef ____call_h__
-#define ____call_h__
+#ifndef ____system_h__
+#define ____system_h__
 
 #include "Tag.h"
 
 namespace jet {
    
-   class __call : public Tag {
+   class __system : public Tag {
    
     public:
-      __call(coreutils::ZString &in, coreutils::MString &out, Global &global);
+      __system(coreutils::ZString &in, coreutils::MString &out, Global &global);
 
     private:
       int pid;