0032121: Draw Harness, ViewerTest - implement -reset option for vlight command

0032121: Draw Harness, ViewerTest - implement -reset option for vlight command

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.