Add support for using a SpaceMouse to pan & zoom in the schematic editor.
Add support for 3Dconnexion SpaceMouse devices to pan & zoom in Eeschema.exe, the schematic editor. The schematic editor commands are exported from the tool manager and can be assigned to 3D mouse buttons and other 3DMouse GUI elements. This implementation is effectively a duplicate of that for pcbnew.exe.
The build option KICAD_USE_3DCONNEXION (default = OFF) is used to control whether the SpaceMouse support is compiled into the solution.
Any limitations to the functionality are limitations of the installed 3Dconnexion driver for the device and OS, effectively making this a Windows and MacOS only solution at the time of writing.