added SignManager class - mostly finished, works so far
added getCount() function to dbPrepared class
  added sql string to cache query
added getDBPool() function to pxnPluginObjects
  make registerListener() public
pxnVaultLink factory() should be static
  now only takes plugin argument

git-svn-id: http://pxncommon.googlecode.com/svn/trunk@27 f5fbd6b6-c213-558c-f92f-5ab434f62466