title: achartengine demo , no trace of R file
body: <p>I am trying to run achartengine demo source on my computer.
  I correctly import the zipfile(achartengine-1.0.0-demo-source.zip) into my workspace as a project.
  there is no gen folder at all.</p>
  
  <p>and I checked; there are <strong>no</strong> "import Android.R" lines.</p>
  
  <p>Then nearly every import line or method gets the "cannot be resolved" error.
  There is a line in the project explorer menu saying "unable to get system library for the project"
  I dunno what to do with that either.</p>
  
  <p>So Eclipse suggests that I import Android.jar to my project and I do that.
  everything seems to be ok but there remains one problem.</p>
  
  <p>There is still error in lines like this</p>
  
  <p>import "org.achartengine.chartdemo.demo.R;"</p>
  
  <p>Yes! Still, There exists no gen folder, thus no R file.</p>
  
  <p>I know a R file has been imported within the android package but I cannot delete it.
  Also I checked and all my resources and xml names are <strong>lowercase</strong>.</p>
  
  <p>Can anybody help me please? :)</p>