title: Source a bunch of files in R script in a nice way
body: <p>I have a script, let say <code>main.R</code>. I have a dozen of function files that I source in the main script. 
  It looks like:</p>
  
  <pre><code>source('doThis.R')
  source('doThat.R')
  source('coolFun.R')
  source('anotherFun.R')
  </code></pre>
  
  <p>...and so on.
  It is not a big problem but I would get rid of it. Should I just make a function <code>sourceAll.R</code> to source everything else and source it in my <code>main.R</code>? Or there are other ways to deal with functions? </p>