Space Mouse Tool for Cura

Description
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This Cura plugin allows to use a 3Dconnexion space mouse to rotate, and pan the camera in Cura.

For the most recent release (v1.3.0 as of now) have a look at [GitHub](https://github.com/FlyingSamson/SpaceMouseTool/releases/latest).

Version v1.2.0 is required for Cura 4.9.0.
Version v1.3.0 is required for Cura 5+

Supported Platforms
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The plugin should work on Mac OSX, Linux, and Windows. I successfully tested it on
* Mac OSX 10.13.6 (High Sierra),
* Ubuntu 16.04 (Xenial),
* Ubuntu 18.04 (Bionic), and
* Window 10 Pro

each running Cura 4.6.1.

If desired I could also provide libs for ARM architectures such as used by the Raspberry Pi B, 2B, and 3B.


State of development
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### Currently implemented
* Free movement (translation and rotation) of the camera around the current rotation center using a free orbit.
* Rotation of camera around the current rotation center using a constrained orbit as already implemented in Cura using standard mous