title: SCons look for files in multiple directories
body: <p>So I'm new to scons and I'm having some trouble with figuring out how I can look in multiple directories? </p>
  
  <p>This is my current approach which works fine for a single folder:</p>
  
  <pre><code>files = File([
      'testfile.c',
      'testfile_const.c',
      'folder/testfile2.c',
      'folder/testfile2_const.c'
  
  ])
  
  
  dir = Dir('.')
  env.Append(CPPPATH = dir)
  env.Prepend(CPPPATH = dir.srcnode())
  Return('files')
  </code></pre>
  
  <p>The thing is, now that i've put <code>testfile2</code> in its own folder, my scons script complains. How can I look for files in another directory?</p>