Add washington and lincoln examples (#67)

Author: banesullivan

Data/lincoln_life_mask/LICENSE

@@ -0,0 +1,30 @@
+Abraham Lincoln Mills Life Mask
+
+Files:
+    lincoln_life_mask.obj  — mesh (150K triangles, 15 MB, OBJ format)
+    lincoln_life_mask.mtl  — material definition
+    lincoln_life_mask_diffuse.jpg
+    lincoln_life_mask_normals.jpg
+    lincoln_life_mask_occlusion.jpg
+
+Subject: plaster life mask of Abraham Lincoln cast by Clark Mills in
+February 1865, approximately two months before Lincoln's assassination.
+
+Collection: Smithsonian.
+
+License: CC0 Public Domain Dedication
+URL: https://creativecommons.org/publicdomain/zero/1.0/
+
+Verbatim from the Smithsonian release:
+    "This media file is in the public domain (free of copyright
+    restrictions). You can copy, modify, and distribute this work without
+    contacting the Smithsonian."
+
+Source pages:
+    https://3d.si.edu/
+    https://sketchfab.com/3d-models/abraham-lincoln-mills-life-mask-a888a9926abb4691a0b91d4eee24b61e
+
+Attribution (courtesy, not required under CC0): "Abraham Lincoln Mills
+Life Mask (1865), Smithsonian, 3D scan released under CC0 Public Domain."
+
+SPDX-License-Identifier: CC0-1.0

Data/lincoln_life_mask/lincoln_life_mask.mtl

@@ -0,0 +1,2 @@
+newmtl m1 
+map_Kd lincoln_life_mask_diffuse.jpg