title: Changing the colors in a contour plot from vis.gam in mgcv
body: <p>I am using <code>vis.gam()</code> to plot the results of a model. The code is the following :</p>
  
  <pre><code>    vis.gam(model,view=c("CHLA","SST"),xlim=c(0,15),ylim=c(10,30),xlab="CHL-a (mg.m-3)",ylab="SST (°C)",plot.type="contour",type="response",color="terrain",n.grid=200)
  </code></pre>
  
  <p>I'd like to set new colors from my own palette as mentioned in the following code :</p>
  
  <pre><code>    # colors palette definition
      jet.colors &lt;-colorRampPalette(c("#00007F", "blue", "#007FFF", "cyan",
                              "#7FFF7F", "yellow", "#FF7F00", "red", "#7F0000"))
  
      vis.gam(model,view=c("CHLA","SST"),xlim=c(0,15),ylim=c(10,30),xlab="CHL-a (mg.m-3)",ylab="SST (°C)",plot.type="contour",type="response",color=jet.colors(10),n.grid=200)
  </code></pre>
  
  <p>Unfortunately, I have this error :</p>
  
  <blockquote>
    <p>Error in vis.gam(model, view = c("CHLA", "SST"), xlim = c(0, 15), ylim = c(10, :
    color scheme not recognised </p>
  </blockquote>
  
  <p>I don't know how to use the <code>jet.colors</code> palette for the function <code>vis.gam</code>...</p>
  
  <p>Thanks for your help !</p>