Fixes issue 3444: window status plugin needs to cache values
issue 3441: twitter plugin needs to cache variables, especially debugEnabled

Change-Id: I116863f2a4e220f330aefeff9f49ed45f698c4d3
Reviewed-on: http://gerrit.dmdirc.com/363
Tested-by: Gregory Holmes <greboid@dmdirc.com>
Reviewed-by: Chris Smith <chris@dmdirc.com>