title: Setting Defaults for geoms and scales ggplot2
body: <p>Theming for ggplot2 makes it quite easy to relegate the need for multiple or repetitive <code>+ opt()...</code> lines. However, I would like to know if there is a way to define defaults for geoms and scale colors. Instead of having to write <code>...+ scale_fill_manual()</code> for each plot, I'd like to be able to set it and forget it. Similarly, I'd like to be able to set geom options so I don't have to retype (or forget to retype) things like <code>geom_text(...,size=3,color="white")</code></p>
  
  <p>Update: </p>
  
  <p>For scales, it seems at some point that there was a method:</p>
  
  <p><code>set_default_scale("colour", "discrete", "grey")</code> </p>
  
  <p>But this function doesn't seem to exist in the most recent version of ggplot2. </p>