title: Incompatible library version RSiena
body: <p>I'm trying to load the RSiena package into R, but keep getting this error message: </p>
  
  <pre><code>Error: package or namespace load failed for ‘RSiena’:
   .onLoad failed in loadNamespace() for 'tcltk', details:
    call: dyn.load(file, DLLpath = DLLpath, ...)
    error: unable to load shared object '/Library/Frameworks/R.framework/Versions/3.4/Resources/library/tcltk/libs/tcltk.so':
    dlopen(/Library/Frameworks/R.framework/Versions/3.4/Resources/library/tcltk/libs/tcltk.so, 10): Library not loaded: /opt/X11/lib/libfontconfig.1.dylib
    Referenced from: /usr/local/lib/libtk8.6.dylib
    Reason: Incompatible library version: libtk8.6.dylib requires version 11.0.0 or later, but libfontconfig.1.dylib provides version 10.0.0
  </code></pre>
  
  <p>I tried installing three ways: 
  <code>install.packages("RSiena")</code>  , <code>install.packages("RSiena", repos="http://R-Forge.R-project.org")</code> , and installing straight from tgz file (from <a href="https://cran.r-project.org/web/packages/RSiena/index.html" rel="nofollow noreferrer">https://cran.r-project.org/web/packages/RSiena/index.html</a>). </p>
  
  <p>The first two installation methods do not give any error and say <code>The downloaded binary packages are in /var/folders/mk/__r_sbzn5mx88x04mrlycsg00000gq/T//RtmpbxlMY8/downloaded_packages</code>.The third option gives this message <code>Error in install.packages : type == "both" cannot be used with 'repos = NULL'</code></p>
  
  <p>None allow me to load the package. I'm working with R version 3.4.3 (2017-11-30) in RStudio Version 1.1.423 on Mac OS X El Capitan (version 10.11.6).</p>
  
  <p>I've tried uninstalling and reinstalling. I'm not sure how else to troubleshoot this issue.</p>