Assemblers, commands and reusability.

    // New design:
    // ??assemblers
    // cmd ==> assembler description (dumpable, reusable for testing)
    // assembler description => QueryCmd
    
    // Just for query execution - not qparse anymore.
    // Utils for
    //   queryString => Query
    //   queryFile => Query
    
    // DB support : => ConnectionDescription.
    
    // == Command-level : QueryCmd
    // querystring/filename
    // syntax :name and symbol
    // output format name
    // graphURLs, namedGraphURLs
    // baseURI
    // .create() => QueryCmdExec creates internal QueryCmdExec (parsed query, loaded dataset)
    
    // == Exec level : QueryCmdExec
    // Model or dataset
    // Query
    // output format
    // .print()
    // .exec()
    
    
    // == remoting
    
    
    //