keep a refcount of gui windows visible..aka which ones want to take focus

if it's != 0 then we'll block input for the game itself (non-gui).

presently only viable for the main menu (and options),
since that's all we've got
close options dialog when we accept it..

shutdown the SDL context on game dtor..make debug methods receive const
ref
shutdown properly
attempt to fix options dialog closing. it's broken though, in hopes

of me understanding how the dialog can delete itself. seems any call
to m_options (the element document) delete results in a crash due
to the event dispatcher still seeing us as being here, even though i called
m_options->close and context()->unloaddocument(m_options). odd stuff.