Added a MultiUndoTask class that is used to enclose multiple undo tasks in a single task.
Added a few encapsulating properties to the SelectionPainOperation.
Fixed the SelectionPaintOperation deforming the selection when the selection was released while moving the mouse.
Modified the FrameView.DisplayFilterPreset() method to allow for filters to be applied only to the current selection.
Added boundaries check on the SelectionPaintOperation.GetCurrentRectangle(), making the selection always be contained within the image boundaries.
Updated change log to reflect recent changes