Fixes for bugs #1019185 and #1017941

Fixes for bugs #1019185 and #1017941
global variable $boxesnew was being corrupted by another function (I don't really see why its even global at this point, its also stored in the Session).  Changed the name of the variable used in the offending function.  The symptoms were that the folder list boxes would not be populated, errors when emptying the trash, and errors in the Folders Options.

git-svn-id: https://svn.code.sf.net/p/squirrelmail/code/trunk/squirrelmail@7996 7612ce4b-ef26-0410-bec9-ea0150e637f0