IMPORT: read SAT, STEP, IGES and WMF files; ACISIN and WMFIN

ACIS text files come in one object per body (3DSOLID, REGION or SURFACE).
STEP B-rep models become a block per product with component inserts at
their placements, scaled to the drawing's units; IGES manifold solids come
in as 3DSOLIDs scaled to the drawing's units with their colours. Splines
that are exactly analytic shapes are kept as those shapes. Windows
metafiles become a WMF<n> block of polylines and text fitted to half the
view, placed at its top-left corner or by WMFIN's insertion prompts. The
Import File window lists the four formats as supported.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

locales/ru-RU/opencadstudio.ftl

@@ -6652,10 +6652,6 @@ txt2mtxt =
 dgn-import =
     .supported = Supported
     .by-extension = By extension
-    .acis-solver = ACIS solver available
-    .export-only = Export only
-    .acis-reason = ACIS bodies are read only inside drawings; SAT files cannot be imported.
-    .step-reason = STEP files are only written (STEPOUT), not read.
     .no-importer = OpenCAD Studio has no importer for this format.
     .recent = Recent:
     .group-2d = 2D / Underlay