0026886: Visualization, TKV3d - eliminate global variables

- AIS_InteractiveContext - create new dummy class field to have an empty TopoDS_Shape object.
- AIS_Point, PrsMgr_PresentableObject - rename static variables to local function variables.
- AIS_Shape, SelectMgr_SelectableObject - remove unused static variables.
- Graphic3d_MaterialAspect, V3d_Viewer - make global static variables as constant.
- V3d_View - move global variable zRotation to class field.
- Move a variable theCurrentSelection as a field of AIS_InteractiveContext and AIS_LocalContext classes. Multiple selection is not used now, so each Context have an own selection.
- Move myStructGenId from Graphic3d_StructureManager to Graphic3d_GraphicDriver for identifying the structures in the driver.
- Move default variable (no shading light) from static value to the class field of OpenGL_View.
Porting note:
- Static methods of AIS_Selection is not used now. Methods of
  AIS_InteractiveContext::InitSelected(),::MoreSelected(),::NextSelected()
  should be used instead of static methods of AIS_Selection.

src/SelectMgr/SelectMgr_SelectableObject.cxx

@@ -183,7 +183,6 @@ void SelectMgr_SelectableObject::ClearSelections(const Standard_Boolean update)
 const Handle(SelectMgr_Selection)& SelectMgr_SelectableObject
 ::Selection(const Standard_Integer aMode) const
 {
-  static Handle(SelectMgr_Selection) bidsel;
   Standard_Boolean Found = Standard_False;
   Standard_Integer Rank=0;
   for (Standard_Integer i=1;i<=myselections.Length() && !Found;i++)