Merge some BS1.7 changes:

internal_solid_infill_pattern

src/mcut/cmake/add_FetchContent_MakeAvailable.cmake

@@ -0,0 +1,7 @@
+macro(FetchContent_MakeAvailable NAME)
+  FetchContent_GetProperties(${NAME})
+  if(NOT ${NAME}_POPULATED)
+    FetchContent_Populate(${NAME})
+    add_subdirectory(${${NAME}_SOURCE_DIR} ${${NAME}_BINARY_DIR})
+  endif()
+endmacro()