[feature] Init the repository and add an importer for "Getaviz A-Frame"

models:

* Add an "Apache" 2.0 license.
* Add a basic scene with a camera, the importer and a placeholder for
meshes.
* Set the ambient lighting to white to make the meshes visible.
* Add an importer for HTML and one for JSON.
* Add an `ImportController.cs` which imports the model when the
application starts.
* Add a `.gitignore` and a `.gitattribute` file to make the "Unity"
project work with "Git" and "Git LFS".
* The `metaData.json` has a lot of entries which have no corresponding
entity in the `model.html`.
* Furthermore, there are duplicate ID's in the `metaData.json`.
* Add a prefab for an `Èntity` which consists of a basic "Unity" box and
the meta data saved in a `Entity.cs` class.

.gitattributes

@@ -0,0 +1,56 @@
+# This file is based on https://thoughtbot.com/blog/how-to-git-with-unity.
+
+# 3D models
+*.3dm filter=lfs diff=lfs merge=lfs -text
+*.3ds filter=lfs diff=lfs merge=lfs -text
+*.blend filter=lfs diff=lfs merge=lfs -text
+*.c4d filter=lfs diff=lfs merge=lfs -text
+*.collada filter=lfs diff=lfs merge=lfs -text
+*.dae filter=lfs diff=lfs merge=lfs -text
+*.dxf filter=lfs diff=lfs merge=lfs -text
+*.fbx filter=lfs diff=lfs merge=lfs -text
+*.jas filter=lfs diff=lfs merge=lfs -text
+*.lws filter=lfs diff=lfs merge=lfs -text
+*.lxo filter=lfs diff=lfs merge=lfs -text
+*.ma filter=lfs diff=lfs merge=lfs -text
+*.max filter=lfs diff=lfs merge=lfs -text
+*.mb filter=lfs diff=lfs merge=lfs -text
+*.obj filter=lfs diff=lfs merge=lfs -text
+*.ply filter=lfs diff=lfs merge=lfs -text
+*.skp filter=lfs diff=lfs merge=lfs -text
+*.stl filter=lfs diff=lfs merge=lfs -text
+*.ztl filter=lfs diff=lfs merge=lfs -text
+# Audio
+*.aif filter=lfs diff=lfs merge=lfs -text
+*.aiff filter=lfs diff=lfs merge=lfs -text
+*.it filter=lfs diff=lfs merge=lfs -text
+*.mod filter=lfs diff=lfs merge=lfs -text
+*.mp3 filter=lfs diff=lfs merge=lfs -text
+*.ogg filter=lfs diff=lfs merge=lfs -text
+*.s3m filter=lfs diff=lfs merge=lfs -text
+*.wav filter=lfs diff=lfs merge=lfs -text
+*.xm filter=lfs diff=lfs merge=lfs -text
+# Fonts
+*.otf filter=lfs diff=lfs merge=lfs -text
+*.ttf filter=lfs diff=lfs merge=lfs -text
+# Images
+*.bmp filter=lfs diff=lfs merge=lfs -text
+*.exr filter=lfs diff=lfs merge=lfs -text
+*.gif filter=lfs diff=lfs merge=lfs -text
+*.hdr filter=lfs diff=lfs merge=lfs -text
+*.iff filter=lfs diff=lfs merge=lfs -text
+*.jpeg filter=lfs diff=lfs merge=lfs -text
+*.jpg filter=lfs diff=lfs merge=lfs -text
+*.pict filter=lfs diff=lfs merge=lfs -text
+*.png filter=lfs diff=lfs merge=lfs -text
+*.psd filter=lfs diff=lfs merge=lfs -text
+*.tga filter=lfs diff=lfs merge=lfs -text
+*.tif filter=lfs diff=lfs merge=lfs -text
+*.tiff filter=lfs diff=lfs merge=lfs -text
+
+# Collapse Unity-generated files on GitHub
+*.asset linguist-generated
+*.mat linguist-generated
+*.meta linguist-generated
+*.prefab linguist-generated
+*.unity linguist-generated

.gitignore

@@ -0,0 +1,36 @@
+[Ll]ibrary/
+[Tt]emp/
+[Oo]bj/
+[Bb]uild/
+[Bb]uilds/
+Assets/AssetStoreTools*
+
+# Visual Studio cache directory
+.vs/
+
+# Autogenerated VS/MD/Consulo solution and project files
+ExportedObj/
+.consulo/
+*.csproj
+*.unityproj
+*.sln
+*.suo
+*.tmp
+*.user
+*.userprefs
+*.pidb
+*.booproj
+*.svd
+*.pdb
+*.opendb
+
+# Unity3D generated meta files
+*.pidb.meta
+*.pdb.meta
+
+# Unity3D Generated File On Crash Reports
+sysinfo.txt
+
+# Builds
+*.apk
+*.unitypackage