title: Include a file within a folder in an Arduino library
body: <p>I'm currently writing an Arduino library and I want to include files in a subdirectory within the library folder. More specifically, I want the files to be accesible from the Arduino sketch.</p>
  
  <p>This is my directory structure:</p>
  
  <pre><code>MyLib/MyLib.cpp
  MyLib/MyLib.h
  MyLib/Extra/SomeNiceFunctions.cpp
  MyLib/Extra/SomeNiceFunctions.h
  </code></pre>
  
  <p>This is how I'm trying to include the file:</p>
  
  <pre><code>#include &lt;MyLib.h&gt;
  #include &lt;Extra/SomeNiceFunctions.h&gt;
  </code></pre>
  
  <p>Obviously this is wrong because of the way the IDE is including the library folders. What else should I try? I could split the Extra folder to another "Library" (another folder) but that's not what I'm after.</p>
  
  <p><strong>EDIT:</strong> This is the error I'm getting <code>undefined reference to 'font8x8'</code>. This is defined in <code>Extra/SomeNiceFunctions.h</code>.</p>