* Add IconTexture/Wrap to INotification (#1738)
Notification record and IActiveNotification interface now supports
setting or updating the texture wraps being used, and SetIconTexture has
gotten more overloads to support leaveOpen mechanism that can commonly
be found with Stream wrappers.
ImGui widget is updated to support testing setting "leaveOpen" and
updating "IconTexture" property via setter, making it possible to check
whether IDTW.Dispose is being called under given conditions.
Some changes to doccomments are made.
* typo