Add BSW / Whitworth (BS 84) rounded thread profiles

[viewinghood]

Summary

• Add proper BSW/Whitworth 55° profiles with rounded crest/root (not UNC + Variant 55), generator, presets, copper icon, and Machining Doctor calculator link
• Bump package version to 2.01
• Related/alternative approach to open PR Added 55 Degree Thread Profile #72 (DrJPK)

Test plan

• Create BSW object; default 1/4-20 preset looks correct
• Spot-check a few other BSW sizes vs chart minors
• Open Online Calculator → Machining Doctor BSW link
• Optional: open _bsw_validation_plots/BSW_1095K104_clean_overlay.FCStd overlay

[viewinghood]

Quick visual of the new form vs the existing ThreadProfile tables (pitch = 1, minor at 0): V60, V45, PG, and BSW Whitworth (55° with rounded crest/root). BSW depth h ≈ 0.640·P = (2/3)H — distinct from truncated-V / Variant-55 approaches.

Cheers,

Richard

[viewinghood]

Small note on the Test plan: the optional _bsw_validation_plots/... path is no longer in this PR (kept slim like PG). The BSW checks themselves (plots, FreeCAD overlays, McMaster BSF compare) live in my ThreadDefinitions work folders BSW_validation_plots and BSW_McMaster — happy to share if useful. The form graphic above is just the quick visual.

[viewinghood]

BSW validation materials (plots, FreeCAD overlays, McMaster STEPs) are on a separate fork branch to keep this PR slim:
https://github.com/viewinghood/ThreadProfile/tree/bsw-validation