 
  desc: Add child to current directory. This cmd is directory dependent, 
        you can only add specific child under specific dir.
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  Add format is directory dependent, each dir can define their own add format.
  
  Add material, particle or gpuprogram:
         
      format: add <type> <name> <scriptFileName>
          
      You can choose script file name from prompt,
      your new created staff will be added into that script.
      Or you can input script name by yourself, 
      system will create a new script file with that name. 
  
      eg: add ParticleSystem fireball0 fireball.particle   // under \particleRoot
          add MaterialSystem glass0 glass.material         // under \materialRoot
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  Add effector, emitter to particle
  
      format: add <type> <detailType>
  
      eg: add Affector LinearForce                    // under \particleRoot\particleName
          add Emitter Point                           // under \particleRoot\particleName    
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  Add technique, pass, tus  to material
    
      format: add <type>
    
      eg: add Technique            // under \materialRoot\materialName
          add Pass                 // under \materialRoot\materialName\technique
          add Tus                  // under \materialRoot\materialName\technique\pass
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  Add gpu program reference to pass
  
      format: add <type> <GpuProgramType> <language> <programName>
                                                      
      eg: add GpuProgramRef vertex_program_ref hlsl flate_vs20
                                                                  
      
