* check in for codegen

        * changed varibles names:
                - GENERIC_IMAGE_BLOCK ---> GENERIC_IMAGE_CODE
                  BLOCK has been changed to CODE. It makes more sence.

                - DATA_TYPE /DATATYPE ---> DT_MACROS
                  All the varibles that are related to the channel
                  data files have been changed.
        * the test files have been updated and channel files and the readme
        to reflex the above change.

        * this is a some small changes in lexer.l and parser.y in an attempt
        to make the code more readable.

        * check in for docs

        * updated to reflex the above changes

        * check in for gegl

        * update the .gil file to reflex the above change