V95 USGS-STYLE EXPORT LABELS

Base
- Starts from V94, which itself starts from stable V90.

Fix
- Fixes the accidental embedded NUL characters in the new PNG save-dialog filter string from V94.

Export improvements
- Ctrl+U USGS-style finite-fault PNG now includes title text, subtitle/statistics, max slip, Mw, patch count, slip colorbar tick labels, a north arrow, and a scale bar.
- Still exports only direct finite-fault stamp patches; secondary deformation remains ignored.

Notes
- Text is rendered into the PNG using Win32 GDI before the existing uncompressed PNG writer saves the image.
