pack_file object
This method will open an existing pack file for reading.
bool open(string filename)
Parameters:
filename
The pack file on disk to open.
Return value:
true on success, false on failure.
Remarks:
When you call this method, the pack file will be opened in read mode. Please note that a pack file cannot be added to once closed unless it is recreated from scratch.
Note that both \ and / can be used to specify paths.
If you pass * to this function, the engine will attempt to open a pack file that has been included into the program itself. For more information on how this is done, see the tutorial on packaging files with your executable.
Example:

    // Open a pack file and extract some data.

    void main()
    {
    pack_file test;
    test.open("pack.dat");
    test.extract_file("t1","test1.txt");
    test.extract_file("t2","test2.txt");
    test.extract_file("t3","test3.txt");
    test.close();
    }