0031701: Visualization, SelectMgr_ViewerSelector - make depth tolerance configurable

0031701: Visualization, SelectMgr_ViewerSelector - make depth tolerance configurable

SelectMgr_ViewerSelector::SetDepthTolerance() - added property defining depth tolerance type and value.
Default value remains the same (SelectMgr_TypeOfDepthTolerance_SensitivityFactor),
while new values (SelectMgr_TypeOfDepthTolerance_Uniform, SelectMgr_TypeOfDepthTolerance_UniformPixels) change behavior.

AIS_Manipulator - removed obsolete suggestion to use AIS_InteractiveContext::SetPickClosest()
for issue fixed long time ago by #0027797.