implement the new security measures for global cache variables that victor and I worked out

All global variables must be initialized within the global scope when the files are loaded. So I added initializations for all the cache variables.

I also enabeld current user caching now since I think that makes it safe.

git-svn-id: http://mantisbt.svn.sourceforge.net/svnroot/mantisbt/trunk@1397 <a class="text" href="/?p=mantisbt.git;a=object;h=f5dc347c">f5dc347c</a>-c33d-0410-90a0-b07cc1902cb9