v0.2.0-preview

Changes since the last preview build:

• Add click-through blocker support
• Improve the toolbar icon
• Fix a tiny memory leak discovered by KSPCF
• Increase accuracy of the Δv calculation with Principia
• Make plot settings and results persistent between scene changes
• Make alarm margin configurable
• Reduce memory usage
• Change arrival time input to time-of-flight
• Several small UI tweaks

Full Changelog: v0.1.0-preview...v0.2.0-preview