Import the ros/ directory of OCCT 6.5.3

 Copy LICENSE from top-level directory.
 Fix permissions (on Unix):

   find * -type f -exec chmod a-x {} \;

   # Windows scripts
   find adm/msvc  -type f -exec chmod a+x {} \;

   # Shell and bat scripts
   chmod a+x draw.bat \
             draw.sh \
             env.bat \
             env.sh \
             custom.bat \
             custom.sh \
             msvc.bat \
             src/DrawResources/demo.bat