Reading Meshes

Be sure to include a README as required from previous projects. Refer
to those assignments for readme requirements.

In addition, which mesh is not visible? Look in the mesh file and
figure out why.  Also, discuss the display mode you implement below.

In this project you will read in a mesh from a file and display it on
the screen.  Mesh files contain a list of vertices followed by a list
of faces.  Sample mesh files can be found on the website. A single
triangle mesh file may look like this:

Number of vertices: 3
0 0 0
1 0 0
0 1 0
Number of faces: 1
0 1 2


Steps

1) Change Orthographic projection to gluOrtho2D(-1,1,-1,1). Make sure
   to change it in reshape also.

2) Provide a method of entering the filename that does not require the
   console window. Use the keyboard to achieve this and likely some
   global variable that detects if you are in 'file name read' mode or
   not.

3) Read in files. Detect bad file names. No crashing from user input.

4) Display the mesh by throwing away the z component. Use
   glBegin(GL_TRIANGLES), glEnd() and use glVertex2f(x,y) in place of
   each vertex.

5) Allow the user to switch to special display mode.  Instead of
   plotting (x,y), plot (-2*x/(z-2) , -2*y/(z-2) ) for a vertex. What
   is this doing? Respond in README.


Extra Credit:
- Incorporate a toggle for wireframe mode
- Incorporate a toggle for backface culling
- Incorporate lighting, flat shading, smooth shading