Ffconverter

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* Added trimesh/gmsh to support 3D-Models (close 11)

* Fixed crash when using drag-and-drop (close 12)

* When set to only show common file types, still show uncommon ones
if no common types are available

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* Added Caching to all_supported_conversions and missing to make
starting the program faster.

* Fix Issue 10: Will now no longer freeze if the external program is
missing when called by progress.py

* Stop a error message by WSL that would display when the program
checks and doesn't find a dependency in WSL

* Will now work with the magick command "convert" installed in WSL

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* Removed unneeded print() left in by accident

* fix imagemagick conversion being broken with old versions of imagemagick

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* Added toggle to use a mobile UI, which has less features
but fits on smaller screens (Linux/Windows Phones)

* Image conversion on Windows doesn't get stuck anymore

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* When running on Windows, the program can now use dependencies that are
installed on WSL (must be enabled in preferences)

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* Should now be compatible with Windows