Fix a bunch of issues reported by coverity that seemed
fairly stright forward and related to rendering

Added an event that fires when the shader updsates so that
programs can use it to update any uniforms they want to

Add methods to override the shader code templates.

Add a method so that users can modify the existing VTK shaders
if desired. In the future will also need to add a method for
users to set uniforms as well and maybe eventually map data arrays
to attributes.

A few fixes and cleanups. Use the Blinn-Phong specular lighting
model in the LightKit and Positional shaders. Old OpenGL uses this
model and it is a decent model. Remind myself that the camera is
positioned at 0,0,0 in view coordinates, had to fix a couple places
that were making different assumptions.

Minor changes to TestVBOPLYMapper to make it easier to use
when testing out changes.

Minor warning and documentation fixes as well.

Change-Id: I8bf108ec18fef2f0a2f83ada8cdf7663086036be

Change-Id: I6bd51fd735edeeea8ad5b16ea5125f588299de47

Change-Id: I52ea4f3f003436fa002ea86962153d5ea4cb532a

Change-Id: I0eb4db5ea193a0afac896418425844cec81e975c

Change-Id: I4d31ad229ef6eb9ee247cae5457e388344248a8f

I am not sure we want to keep it this way, we can just copy over
the logic from the painters to generate normals as this adds a
whole new module for one filter.

Change-Id: Ied4680bd05e32d01228f8dacfa1cb8309a5840ac

This should add it to the branch, the scene topic already pushed it
into the external data store.

Change-Id: Ic9888225c77459ebb0780eaa24d13b33896a9a65

Change-Id: I3c62b6ce39afcb3f1abe59811f89e9064b23456d

This makes use of the code developed for the scene, but ports it to
a more direct use of VBOs in the derived poly data mapper.

Change-Id: Idb0db244abbb0e6857818589b20aae22e10abd53