TacticalGraphics objects drift from cursor during dragging

[zglueck]

Some TacticalGraphics, specifically screen size constant objects, will drift during dragging.

[zglueck]

Changed the MilStd2525PointGraphic to use a screen size constant dragging method in 665af51.

Other TacticalGraphics primarily display as globe size constant objects (e.g. they remain geographically presented) and should use the globe size constant drag method (the current implementation). In some cases the label connected to the TacticalGraphic will be the drag object. As labels exhibit screen size constant behavior, drifting may occur when dragging a geographic TacticalGraphic with screen size constant label. At this time, TacticalGraphic will retain the globe size constant method for dragging as it best handles dragging of geographic referenced objects.