vlight command has been revised to provide more friendly syntax.
Command now accepts light index or name as first argument.
Added arguments -enable/-disable for managing enabled state.
Added argument -reset to reset light parameters to default values.
V3d_Viewer::SetDefaultLights() now sets names "headlight" and "ambient" to created lights.
Graphic3d_TypeOfLightSource enumeration values have been renamed to avoid shortcuts.
Draw::Atof(), applied corrections to avoid explicit new/delete calls.
Added new class AIS_LightSource representing a light source presentation.
Graphic3d_TMF_CameraPers - added new mode to Graphic3d_TransformPers
defining 3D point relative to camera Eye position
