removed ex_ from example names

Envelope_3/doc_tex/Envelope_3/envelope.tex

@@ -238,7 +238,7 @@ traits classes is demonstrated in the next section.
   </center>
 \end{ccHtmlOnly}
 \caption{(a)~Two triangles in ${\mathbb R}^3$, as given in
-\ccc{ex_envelope_triangles.cpp}. (b)~Their lower envelope.
+\ccc{envelope_triangles.cpp}. (b)~Their lower envelope.
 (c)~Their upper envelope.\label{env3_fig:ex_tri}}
 \end{figure}
 
@@ -251,7 +251,7 @@ For convenience, we use the traits-class decorator
 \ccc{Env_surface_data_traits_3} to label the triangles. When
 printing the diagrams, we just output the labels of the triangles:
 
-\ccIncludeExampleCode{Envelope_3/ex_envelope_triangles.cpp}
+\ccIncludeExampleCode{Envelope_3/envelope_triangles.cpp}
 
 \subsection{Example for Envelope of Spheres}
 
@@ -261,7 +261,7 @@ envelope-traits class for spheres, based on the
 curves. The program reads a set of spheres from an input file and
 constructs their lower envelope:
 
-\ccIncludeExampleCode{Envelope_3/ex_envelope_spheres.cpp}
+\ccIncludeExampleCode{Envelope_3/envelope_spheres.cpp}
 
 \subsection{Example for Envelope of Planes}
 
@@ -269,4 +269,4 @@ The next example demonstrates how to instantiate and use the
 envelope-traits class for planes, based on the
 \ccc{Arr_linear_traits_2} class that handles infinite linear objects such as lines and rays.
 
-\ccIncludeExampleCode{Envelope_3/ex_envelope_planes.cpp}
+\ccIncludeExampleCode{Envelope_3/envelope_planes.cpp}