1. Fixed a warning where $f_private was used without being defined when
   adding a public bug note.
2. Improved the admin_upgrade.php + enhanced the upgrade class to
   support generation of SQL files, fancy printing, and facy printing + execution.
   From now on, when we change the db format (till v0.18.0), we should change
   the file admin_upgrade_0_18_0 and add the new SQL. Before releasing we
   can update the db_upgrade.sql if we want using the SQL generation feature.

git-svn-id: http://mantisbt.svn.sourceforge.net/svnroot/mantisbt/trunk@1089 <a class="text" href="/?p=mantisbt.git;a=object;h=f5dc347c">f5dc347c</a>-c33d-0410-90a0-b07cc1902cb9