Add default_project/profile.
When setting up t_prefs object, we should use ->Get Method instead of calling config_get directly to handle default values set when creating the object.

git-svn-id: http://mantisbt.svn.sourceforge.net/svnroot/mantisbt/trunk@3676 <a class="text" href="/?p=mantisbt.git;a=object;h=f5dc347c">f5dc347c</a>-c33d-0410-90a0-b07cc1902cb9