elect a directory.

<h4>Process Model</h4>
<p>This dropdown list allows you to specify how operating system processes are
   used in loading and running the tests in this project. Four settings are
   defined:
   <ul>
   <li>The <b>Default</b> setting refers to the option selected by the user
       on the Assembly Isolation page of the NUnit Settings Dialog.
   <li><b>Single</b> means that tests are run in a test domain in the
   	   same process as NUnit. This is the way previous versions of NUnit
	   ran