COMP: avoid building CGAL ImageIO lib (fixes #15)

- OpenFOAM doesn't use any of the CGAL image library and the ImageIO
  library adds in an unnecessary OpenGL dependency (reported to fail
  on kubuntu-14.04)

STYLE: adjust documented link to main (non-svn) VisIt project directory

BUILD.md

@@ -415,7 +415,8 @@ The minimum gcc/g++ requirements for building various components.
 [link FFTW]:      http://www.fftw.org/fftw-3.3.5.tar.gz
 
 [page cgns]:      http://cgns.github.io/
-[link ccmio]:     http://portal.nersc.gov/svn/visit/trunk/third_party/libccmio-2.6.1.tar.gz (check usage conditions)
+[link ccmio]:     http://portal.nersc.gov/project/visit/third_party/libccmio-2.6.1.tar.gz (check usage conditions)
+[altlink ccmio]:  http://portal.nersc.gov/svn/visit/trunk/third_party/libccmio-2.6.1.tar.gz (check usage conditions)
 
 [page tecio]:     http://www.tecplot.com/
 [link tecio]:     http://www.tecplot.com/my/tecio-library/ (needs registration)

makeCGAL

@@ -475,6 +475,7 @@ CMAKE_OPTIONS
         -DCMAKE_INSTALL_PREFIX=$CGAL_ARCH_PATH \
         -DCGAL_INSTALL_LIB_DIR=lib$WM_COMPILER_LIB_ARCH \
         -DCMAKE_BUILD_TYPE=Release \
+        -DWITH_CGAL_ImageIO=OFF \
         -DWITH_CGAL_Qt5=OFF \
         ${optHeadersOnly:+-DCGAL_HEADER_ONLY=TRUE} \
         $configBoost $configGmp $configMpfr \