DWF and DGN underlays: attach, display, snaps, frames and references

DWFATTACH / -DWFATTACH and DGNATTACH / -DGNATTACH attach a DWF / DWFx sheet
or a DGN (V7 or V8) model with the reference's prompts; ATTACH routes the
file types to them. The sheet or model is read into vector paths, drawn as a
transparent underlay raster (contrast, fade, monochrome and background
adjustment apply) and offers its geometry to object snaps. Definitions are
kept in ACAD_DWFDEFINITIONS / ACAD_DGNDEFINITIONS, the External References
palette lists and reloads them, and image textures get line-keeping mip
levels so thin underlay lines stay visible when zoomed out.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/locale_catalog.rs

@@ -3771,6 +3771,10 @@ pub(super) fn message_attribute(source: &str) -> Option<(&'static str, &'static
         "Opened drawing, but recent copy could not be stored: {error}" => Some(("common", "opened-drawing-but-recent-copy-could-not-be-stored")),
         "Select PDF Underlay" => Some(("common", "select-pdf-underlay")),
         "PDF Files" => Some(("common", "pdf-files")),
+        "DWF Files" => Some(("common", "dwf-files")),
+        "DGN Files" => Some(("common", "dgn-files")),
+        "Select DWF File" => Some(("common", "select-dwf-file")),
+        "Select DGN File" => Some(("common", "select-dgn-file")),
         "PDFATTACH: {e}" => Some(("common", "pdfattach")),
         "Select External Reference File" => Some(("common", "select-external-reference-file")),
         "CAD Files" => Some(("common", "cad-files")),
@@ -4495,6 +4499,8 @@ pub(super) fn message_attribute(source: &str) -> Option<(&'static str, &'static
         "1 layout selected" => Some(("common", "value-1-layout-selected")),
         "layouts selected" => Some(("common", "layouts-selected")),
         "PDF" => Some(("common", "pdf")),
+        "DWF" => Some(("common", "dwf")),
+        "DGN" => Some(("common", "dgn")),
         "Select the layouts to output. Each page is printed in Layout mode." => Some(("common", "select-the-layouts-to-output-each-page-is-printed-in-layout-mode")),
         "Select all" => Some(("common", "select-all-1fc9a3")),
         "Select none" => Some(("common", "select-none")),