Added ZString.c_str() function; Added MStrin operator=.

MString.h

@@ -7,7 +7,9 @@ namespace coreutils {
 
    ///
    /// Use the MString object when you need a permanent backing store on the heap 
-   /// for a ZString style functionality.
+   /// for a ZString style functionality. Because MString has a backing store we
+   /// added functionalities to build strings as well as the parsing power of the
+   /// ZString.
    ///
    
    class MString : public ZString {
@@ -48,8 +50,22 @@ namespace coreutils {
 
       ~MString();
 
+      ///
+      /// Assignment operator will copy data to backing store.
+      ///
+
+      MString& operator=(coreutils::ZString& data);
+
+      ///
+      ///
+      ///
+      
       int write(char ch);
 
+      ///
+      ///
+      ///
+      
       int write(ZString &value);
       
     private: