fix for 0005425: Private projects don't allow users who have been added to the
project use the project...

• specifically projects that are defined as subprojects
  • changed user_get_accessible_projects() to return all projects
    the user has access to regardless of hierarchy

git-svn-id: http://mantisbt.svn.sourceforge.net/svnroot/mantisbt/trunk@3566 <a class="text" href="/?p=mantisbt.git;a=object;h=f5dc347c">f5dc347c</a>-c33d-0410-90a0-b07cc1902cb9