mousegen-0.7

Enable --mousecape-theme --update-existing

Highlights:

• MousecapeTheme: Load and update existing theme
• Implement MousecapeReader (and reuse it in MousecapeDumpProvider)
• BitmapOutputBuilder: Save hotspots in *.cursor config (xcursorgen) files
• SVGCursorMetadata: Allow multiple references to single align-anchor definition
• SVGSizing: Adjust hotspot rounding heuristics

Full Changelog: mousegen-0.6.3...mousegen-0.7