0030523: Visualization - Highlighting does not work anymore

0030523: Visualization - Highlighting does not work anymore

Added hints about ZLayer consideration and changing highlight colors to documentation
of AIS_InteractiveContext::SetHighlightStyle() method.

AIS_InteractiveContext::MoveTo() now checks if highlighting style does not use immediate layer
and performs full Redraw() instead of RedrawImmediate().

Improved parsing of ZLayer names within vdisplay, vzlayer and vselprops commands.
vreadpixel now reports syntax errors on wrong input.