Fix viewer dependencies, shapes, and transparency (#41)

* In tesseract_viewer_python setup.py parse package.xml for version instead of using cmake configure file

* Add missing opencv-contrib-python requirement in viewer setup.py

* Fix mesh indices order for shape meshes in viewer

* Enable alphaMode BLEND for gltf2 meshes so transparency works correctly

Author: johnwason

tesseract_viewer_python/setup.py

@@ -18,6 +18,6 @@
       packages=['tesseract_robotics_viewer','tesseract_robotics_viewer.resources'],
       package_data={'tesseract_robotics_viewer.resources':['static/index.html','static/app.js','geometries.json']},
 	  license='Apache-2.0',
-	  install_requires=['numpy','tesseract_robotics'],
+	  install_requires=['numpy','tesseract_robotics','opencv-contrib-python'],
 	  long_description='Tesseract Robotics viewer package for Python'
      )