STEP: Implementation ported from BambuStudio:

CMake handling is different

STEP: Removed preprocessing stage

STEP: Small refactoring

STEP: Bigger refactoring

STEP: Changed naming on loaded object and volumes:
If the STEP contains exactly one named volume, the object and its first
volume will both have that name. Otherwise, filename w/o suffix is used
as object name and volumes are named using names from the STEP (if there
is none, untranslated "PartN" string is used).

STEP: Load the libraries dynamically on Win

wip

src/libslic3r/CMakeLists.txt

@@ -94,6 +94,8 @@ add_library(libslic3r STATIC
     Format/STL.hpp
     Format/SL1.hpp
     Format/SL1.cpp
+    Format/STEP.hpp
+    Format/STEP.cpp
     GCode/ThumbnailData.cpp
     GCode/ThumbnailData.hpp
     GCode/Thumbnails.cpp