* INSTALL.txt: added a hint how to install the converter and its requirements. * doku/source/conf.py, doku/source/INSTALL.txt, doku/source/index.txt,doku/source/restrictions.txt, doku/source/index.rst,doku/source/restrictions.rst: renamed .rst to .txt, linked INSTALL.txt from root into the docs.

SYMBOLSET
    # basic symbol for hatching in all variantes which
    # will be combined inside the STYLE-block
    SYMBOL
      NAME "hatch"
      TYPE hatch
    END
END