[REVIEW 3-5] xlsx make imported controls non-visible ( when marked as hidden )

[Noel Power]

please consider this for 3.5, the vmldrawing 'style' part can specifiy 
if the drawing is 'hidden' while I am not sure what we can do with 
normal shapes certainly for controls there is the 'EnableVisible' 
property which can be applied. This patch ensures hidden controls are 
indeed hidden ( and not cluttering up the screen or covering other 
content etc. )

Noel