Move buildmaterial to OsgMaterial to make it more accessible
Add copyright to shader
Add shader and code for unlit text
Remove unneeded include files
Fixed comment
Add serialization for axes representation
Add Unittest
Merge branch 'fix/unlit-text' into 'master'

Correct shading for hud text

+1: Julien Lenoir, Wesley Turner, Gughan Sathyaseelan

Merged-on: https://www.assembla.com/code/OpenSurgSim/git/merge_requests/1345193
Merge branch 'feature/serialize-axes' into 'master'

Add serialization for Graphics::AxesRepresentation

Merged-on: https://www.assembla.com/code/OpenSurgSim/git/merge_requests/1362923