title: change distance of x-axis labels from axis in sciplot bargraph
body: <p>I'm constructing a plot using bargraph.CI from sciplot. The x-axis represents a categorical variable, so the values of this variable are the names for the different positions on the x-axis. Unfortunately these names are long, so at default settings, some of them just disappear. I solved this problem by splitting them into multiple lines by injecting "\n" where needed. This basically worked, but because the names are now multi-line, they look too close to the x-axis. I need to move them farther away. How?</p>
  
  <p>I know I can do this with mgp, but that affects the y-axis too.</p>
  
  <p>I know I can set axisnames=FALSE in my call to barplot.CI, then use axis to create a separate x-axis. (In fact, I'm already doing that, but only to make the x-axis extend farther than it would by default- see my code below.) Then I could give the x-axis its own mgp parameter that would not affect the y-axis. But as far as I can tell, axis() is well set up for ordinal or continuous variables and doesn't seem to work great for categorical variables. After some fiddling, I couldn't get it to put the names in the right locations (i.e. right under their correspondence bars)</p>
  
  <p>Finally, I tried using mgp.axis.labels from Hmisc to set ONLY the x-axis mgp, which is precisely what I want, but as far as I could tell it had no effect on anything.</p>
  
  <p>Ideas? Here's my code.</p>
  
  <pre><code>ylim    = c(0.5,0.8)
  yticks  = seq(ylim[1],ylim[2],0.1)
  ylab    = paste(100*yticks,"%",sep="")
  
  bargraph.CI( 
      response    = D$accuracy,
      ylab        = "% Accuracy on Test",
      ylim        = ylim,
      x.factor    = D$training,
      xlab        = "Training Condition",
      axes        = FALSE
      )
  axis(
      side        = 1,
      pos         = ylim[1],
      at          = c(0,7),
      tick        = TRUE,
      labels      = FALSE
      )
  axis(
      side        = 2,
      tick        = TRUE,
      at          = yticks,
      labels      = ylab,
      las         = 1
      )
  </code></pre>