Initial release

Consider this somewhere between alpha and beta quality:
some things work and are practically usable, some things are broken
and some things need further refactoring which will impact the plugin API
and/or Blender scene setup. No verification has also been done at this
point that the renders produced match the underlying data in the correct
way (although at first glance they do match).

Brief list of features (and remarks), see readme.md for more information:

• Scene elements
  • Polygonal geometry, i.e. Blender meshes
  • Subdivision surfaces: these are handled by Blender's dependency graph mechanism,
    but this triangulates the geometry instead of passing the subdivision control
    cage to OSPRay (which also has subdiv support).
  • Currently no specific support for other non-polygonal objects (e.g. text, curves, ...),
    if it works it's due to the dependency graph mechanism
  • Object transformations and parenting
  • Instancing: for large numbers of instances there currently is
    quite a high overhead in terms of scene setup and memory usage
  • Point, sun, spot and area lights. No support for OSPRay's HDRI light yet
  • Vertex colors on Blender meshes
  • Node-based material editing for a subset of OSPRay materials,
    using nodes from the OSPRay sub-menu. Note that connecting
    nodes to input ports, like a color, will not work as expected
    when a connection is made (and there is no way to hide the sockets to signal this).
    Also, although most of the Cycles nodes are still available in the
    shader editor almost NONE of those nodes will work.
• Rendering
  • Supports OSPRay's SciVis and Path Tracer renderers, and most of
    their settings
  • Final render (F12), including canceling
  • Interactive preview render works with respect to viewpoint changes,
    but most other scene changes will NOT update in the rendered view.
    Switching out and back into rendered view should sync to the updated scene
  • The view will match in orthographic and "free" view mode, but it is
    incorrect when viewing through a camera
  • Border render (i.e. render only part of an image) currently only works
    for final render, not for interactive render
  • Simultaneous rendering modes in Blender are not supported. E.g. multiple
    3D views each in interactive rendering mode will not work as the render
    server does not support this
  • Material/light/... preview rendering does not work
• Camera
  • Perspective and orthographic cameras, plus OSPRay's panoramic camera.
    The latter is similar to Cycles' equirectangular camera, but without
    any parameters to tweak
  • Depth of field
• Blender UI
  • Integration within UI, mostly panels for editing properties and such,
    is not very advanced. Some properties are currently only settable using Blender
    custom properties
    on objects and meshes.
• Rudimentary support for BLOSPRAY-specific volume, geometry and scene plugins
• Rudimentary transfer function editing for volume data (by mis-using the ColorRamp node)

Notes on current (2.0.x alpha) OSPRay, not BLOSPRAY, limitations:

• When using the scivis renderer a transformed volume will not render
  correctly