Release v0.3.0

What's Changed

• feat: Implement advanced layer-based auto-layout by @filmil in #19
• feat: Implement SVG and PDF output formats by @filmil in #21
• fix: bundle luxisr font for draw2d text rendering by @filmil in #20
• feat: implement constraint-based layout and refine IEEE graphics by @filmil in #22
• feat: implement A* obstacle-avoiding router by @filmil in #23

Full Changelog: v0.2.0...v0.3.0