BUG: Fixed the gl stack underflow error.

STYLE: Minor tweaks to the UI.

BUG: Fixed issue when applying invalid image.

The main issue with inf/nan seems to be in calculating the bounds of the
points. I have created a structure to store a list of bad points, and
then a function to calculate the bounds ignoring these bad points. After
talking to Utkarsh we decided that bad points should be kept, and breaks
in the line plot should appear. This will require further testing, and
possibly some extra logic in the rendering code (works for me).

the loop order.

Added support for cell types VTK_POLYGON and
VTK_CONVEX_POINT_SET.

ENH:Update glext.h from version 59 (2010/02/10) to version 60 (2010/03/11) from http://opengl.org/registry.

ENH:Draft version of OpenGL 3.1/3.2/3.3/4.0 header file (2010-03-11 11:19:31 -0800) from http://www.opengl.org/registry

ENH:Draft version of OpenGL 3.1/3.2/3.3/4.0 header file (2010-02-10 22:22:53 -0800) from http://www.opengl.org/registry

ENH:Update glext.h from version 58 (2010/02/03) to version 59 (2010/02/10) from http://opengl.org/registry.

ENH:Update glxext.h from version 26 (2010/01/20) to version 27 (2010/02/10) from http://opengl.org/registry.

After talking with Brad King it is clear that the visibility support is
also useful for static linking.

This still requires some more work to take into account font metrics for
the axis being rendered. This fix uses the axis position variable to
determine the correct offset/position of the labels.

GetSize was not the size I was expecting (STL/Qt API). Changed to
GetNumberOfTuples and all is much better again.

Added the option to turn on stricter compiler flags (GCC only right
now), default to off. The flags are quite safe in VTK, but can cause
hundreds of warnings in some other projects code bases.