Class STEPCAFControl_Writer is corrected to avoid replacing non-Ascii symbols by question marks, and spaces by underscores, on export to STEP.
Related: DRAW commands dealing with strings in OCAF documents are corrected to pass Unicode symbols as UTF-8.
Off-topic: code saving names of external STEP files in XDE and fetching them back is corrected to preserve Unicode symbols as UTF-8.
Added test bugs xde bug31851
Test de step_4 E7 corrected (no more replacement of spaces by underscores in names of layers)
ae9f4b64ca