title: googleVis: Colors with alpha < 1
body: <p>I am trying to use some colors with alpha &lt; 1 in googlevis chart without success.</p>
  
  <p>My initial Color List that is applied is: </p>
  
  <pre><code>MyColors &lt;- c('#DD4477', '#109618', '#AAAA11)
  </code></pre>
  
  <p>Then I apply the function adjustcolor: <code>MyAlphaColors &lt;- adjustcolor(MyColors, 0.4)</code></p>
  
  <p>If I try to use these colors in a googlevis chart I get the error: #109618E6 is not a valid color string</p>
  
  <p>How could I overcome this problem and use some colors with alpha &lt; 1 in my googlevis charts?</p>
  
  <p>Here is a reproducible example (in that particular case I don't get the error message but the second series colors are not plotted properly):</p>
  
  <pre><code>library(googleVis)
  MyColors &lt;- c('#DD4477', '#109618', '#AAAA11')
  
  df &lt;- data.frame(country=c("US", "GB", "BR"), val1=c(10,13,14), val1.style = MyColors, val2=c(23,12,32), val2.style = adjustcolor(MyColors, 0.4))
  
  plot(gvisColumnChart(df, xvar="country", yvar=c(colnames(df)[2], colnames(df)[3], colnames(df)[4], colnames(df)[5]),
                       options=list(legend="none",
                                    chartArea = "{left:'10%',top:'10%',width:'80%',height:'70%'}",
                                    height=750,
                                    width=1050,
                                    backgroundColor = "white")
                       )
      )
  </code></pre>