Feature Request - Pcbnew: An easy way to enable exporting multiple pcb-outlines to one step file

Description

Try to export multiple edge-cuts as pcb-outlines as one step-file

Steps to reproduce

  1. PCBnew: Create multiple outlines in Edge.Cuts, e.g. 3 pcbs:

pcbnew_3pcbs_2020-12-09

  1. 3D Viewer shows 3 pcbs:

3d_viewer_3pcbs_2020-12-09

  1. Exporting to step does show (first) 1 pcb-outline only

freecad_1pcb_only_step_2020-12-09

Please, extension to export multiple pcb-outlines to one step-file would be much appreciated.

Thanks for all your good work.

KiCad Version

Version: 5.1.8-db9833491~88~ubuntu20.04.1, release build
Libraries:
    wxWidgets 3.0.4
    libcurl/7.68.0 OpenSSL/1.1.1f zlib/1.2.11 brotli/1.0.7 libidn2/2.2.0 libpsl/0.21.0 (+libidn2/2.2.0) libssh/0.9.3/openssl/zlib nghttp2/1.40.0 librtmp/2.3
Platform: Linux 5.7.1-050701-generic x86_64, 64 bit, Little endian, wxGTK
Build Info:
    wxWidgets: 3.0.4 (wchar_t,wx containers,compatible with 2.8) GTK+ 3.24
    Boost: 1.71.0
    OpenCASCADE Community Edition: 6.9.1
    Curl: 7.68.0
    Compiler: GCC 9.3.0 with C++ ABI 1013

Build settings:
    USE_WX_GRAPHICS_CONTEXT=OFF
    USE_WX_OVERLAY=ON
    KICAD_SCRIPTING=ON
    KICAD_SCRIPTING_MODULES=ON
    KICAD_SCRIPTING_PYTHON3=ON
    KICAD_SCRIPTING_WXPYTHON=ON
    KICAD_SCRIPTING_WXPYTHON_PHOENIX=ON
    KICAD_SCRIPTING_ACTION_MENU=ON
    BUILD_GITHUB_PLUGIN=ON
    KICAD_USE_OCE=ON
    KICAD_USE_OCC=OFF
    KICAD_SPICE=ON