[power-pro] dialog plugin 0.88

[entropyreduction]

-- Probably fixed problem with dialogs containing activeX controls
crashing PowerPro on exit.

-- …and another, where dlgHan.get_hwnd() crashed 

-- For listViews, get_value(<target>, "selectedAllIndex") is now
get_value(<target>, "selectedIndex" [, <howMany>]) with <howMany> -1

-- Corrected documentation for listViews set_value(<target>, "item", 

-- Tightened up rules on effects of the configuration ini file key
indexBase, and of the set_base service; documentation notes effects
wherever relevant

-- Added get_base service.  All scripts that require set_base(1) on
entry now revert to current base if required on exit.