  TN5250J launch Customized External Program function

requirement:
 TN5250J user want to launch Customized external program from tn5250j.

scenario:
 need following steps to finish this requirement.
 1 format Launch String to launch Customized external program.
   for example: PDFViewer:parameter1,parameter2,parameter3
         acroread Z:\share\pdf\chapter1.pdf
 
 2 make Launch String to become a hotspot.

 3 when user click hotspot, system check whether it's a Launch String, if it is a Launch String, System  
 automatically launch Customized external program with parameters which come from Launch String. 

 4 Configure Customized External Program, system allow user to configure Customized External Program name, window   
   command and unix command.

implementation:
 1: generate Launch String.
        
 2: modify ScreenPlanes.java's method checkHotSpots

        3: modify OperatingSystem.java's method displayURL

 4: modify Connect.java methods
          Connect class's Construction method, 
          CreateExternalProgramPanel,
          actionPerformed,  
             saveProps
           create ExternalProgramConfig.java
           modify tn5250jMsgs.properties
           create tn5250jExternalProgram.properties
 