Fix erroneous SetCapture after COptionMenu::onMouseDown

[nickdowell]

Fixes #302

COptionMenu::onMouseDown returns kMouseDownEventHandledButDontNeedMovedOrUpEvents

Prior to release 4.11, Win32Frame::proc would not call SetCapture in response:

vstgui/vstgui/lib/platform/win32/win32frame.cpp

Lines 778 to 779 in 6431f63

	if (pFrame->platformOnMouseDown (where, buttons) == kMouseEventHandled && getPlatformWindow ())
	SetCapture (getPlatformWindow ());

In 4.11 and onwards, only event.consumed is being checked, so kMouseDownEventHandledButDontNeedMovedOrUpEvents results in a call to SetCapture which leads to the behavious described in #302:

vstgui/vstgui/lib/platform/win32/win32frame.cpp

Lines 833 to 834 in addf12b

	if (event.consumed && getPlatformWindow ())
	SetCapture (getPlatformWindow ());

This PR adds a !event.ignoreFollowUpMoveAndUpEvents () check so that SetCapture is not called in response to kMouseDownEventHandledButDontNeedMovedOrUpEvents.