message: Add VTK auto-init call, which avoids VTK context error message
  Previously complained:
  Error: no override found for 'vtkContextDevice2D`
diff: find_package(Eigen3 REQUIRED)
  +
  # Add as "system headers" to avoid warnings generated by them with
  # compilers that support that notion.
  include_directories(SYSTEM ${EIGEN3_INCLUDE_DIR})
  find_package(OpenGL REQUIRED)
  find_package(GLEW REQUIRED)
  include_directories(SYSTEM ${OPENGL_INCLUDE_DIR} ${GLEW_INCLUDE_DIRS})
  +
  if(WIN32 AND NOT BUILD_SHARED_LIBS)
  add_definitions(-DGLEW_STATIC)
  endif()
  @@ -36,3 +38,8 @@ target_link_libraries(AvogadroVtk AvogadroRendering AvogadroQtGui
  VTK::RenderingOpenGL2 VTK::GUISupportQt VTK::RenderingVolumeOpenGL2
  VTK::RenderingFreeType VTK::InteractionStyle VTK::ChartsCore VTK::ViewsContext2D
  VTK::RenderingContextOpenGL2 VTK::DomainsChemistryOpenGL2 Qt5::Widgets)
  +
  +vtk_module_autoinit(TARGETS AvogadroVtk MODULES
  + VTK::RenderingOpenGL2 VTK::GUISupportQt VTK::RenderingVolumeOpenGL2
  + VTK::RenderingFreeType VTK::InteractionStyle VTK::ChartsCore VTK::ViewsContext2D
  + VTK::RenderingContextOpenGL2 VTK::DomainsChemistryOpenGL2 Qt5::Widgets)
  \ No newline at end of file
  