Fixes #2000

Fixes #1866

Fixes #1866

This is a typical blender asset usage approach.  Linked
content can be included in a new blend file but it cannot be edited in
the file that links it.

Upgraded the blender exporter to understand linked groups and add them
to an exported scene.

Added "webgl_loader_scenegroup_blender.html".  This example shows
blender linked groups to demonstrate changes made to the
blender exporter.  The table.blend links an object group (cup and
silverware) from the dinnerset.blend file.  This example does not
incorporate the location offsets in the group definition which it really
should.  Being a new threejs user I did not know how best to do it.

- removed not anymore existing ro.me specific remains (triggers, mesh colliders and shadow volumes)
- added custom properties for setting shadow map casting and receiving, depthWrite, depthTest, blending, doubleSided
- using Blender native "transparency" checkbox for setting out "transparent" property
- better handling of messed up texture slots

Fixed Blender importer to work with Blender 2.60, add option for importing workers or non-worker models.

Fixed more examples to use worker-less format. All examples should work now.

Only Max exporter should be left to change.

* Added support to texture.offset in CanvasRenderer
* Removed ShadowVolume, ShadowVolumeDynamicMaterial and LensFlare classes.
* Removed Stencil Shadows and LensFlare code out of WebGLRenderer
* Added 2.59 folder to Blender, and removed old ones.

Again, not to be used yet, very little tested plus code is horrible.

Extended Blender exporter to support mesh merging and export of all / selected meshes as single JSON model.

Do not use yet, work-in-progress, very little tested.

Gah, these things are pain to debug - "undefined" value in uniforms can lead to very weird behaviors.

(normal maps, textures packed in blend file, copy textures, urlBaseType, texture params)

Also fixed broken reload handling and bumped up version number.

	new file:   2.58/scripts/addons/io_mesh_threejs/__init__.py
	new file:   2.58/scripts/addons/io_mesh_threejs/export_threejs.py
	new file:   2.58/scripts/addons/io_mesh_threejs/import_threejs.py

Blender normal map support is work-in-progress:
 - for individual models normal map shader will need to be refactored to use standard scene lights
 - would be nice to handle also bump maps (a lot of Blender assets do not use "use_normal_map" flag on tangent space normal texture but instead use "use_map_normal" flag on texture slot of grayscale heightmap texture)

Also some whitespace cleanup.

Blender exporter: added handling of textures packed into blend file, fixed some texture location edge cases.

Blender (2.57) export scripts now exports a default camera, if no camera in the scene was selected for export (in scene export). The default camera property is also updated accordingly.

Blender (2.57) export script now add cameras to the scene output. (Note: Very buggy and target/lookat is broken.)

Also fixed default camera buggy string in Blender scene exporter and changed lightmap parameter name in base Loader (to be consistent with other "maps").

Updated Blender scene exporter to output proper JSON. Changed OBJ converter to dump less digits for floats.

Added support for empty objects and meshes without geometries to Blender scene exporter and SceneLoader.