title: Error trying to load a package in Rstudio
body: <p>I am trying to install the CosmoPhotoz package on a new macbook pro. I have never had an issue installing packages in R and Rstudio so I am not sure how to go about fixing this error.       </p>
  
  <pre><code>    install.packages("CosmoPhotoz", repos="http://cran.rstudio.com/", 
      dependencies=TRUE)
      library(CosmoPhotoz)
  </code></pre>
  
  <p>This is the error message:</p>
  
  <pre><code> Error in loadNamespace(i, c(lib.loc, .libPaths()), versionCheck = vI[[i]]) : 
   namespace ‘htmltools’ 0.2.6 is being loaded, but &gt;= 0.3 is required
   In addition: Warning messages:
   1: replacing previous import by ‘grid::arrow’ when loading ‘ggthemes’ 
   2: replacing previous import by ‘grid::unit’ when loading ‘ggthemes’ 
   3: replacing previous import by ‘scales::alpha’ when loading ‘ggthemes’ 
   Error: package or namespace load failed for ‘CosmoPhotoz’
  </code></pre>