Release v0.3.0

Changes in this Release

• minimum yt version is now 4.1
• Added isocontour shader by @sochowski in #40
• Block-rendering based slicing by @matthewturk in #13
• Curve plotting by @chrishavlin in #26
• Pop-up help by @chrishavlin in #44
• allow uniform arrays by @matthewturk in #38
• Make windows resizable by @matthewturk in #57

Full Changelog: v0.2.3...v0.3.0