Splice v3.0.0-alpha.0

• Add test temporary directory to .gitignore. See #85.
• Upgrade riffle to 2.0.0-alpha.4. Closes #97.
• Add chicklets and links to README.md. Closes #85.
• Build with Actions, ship coverage to Codecov. Closes #82. Closes #83.
• Add .npmignore. See #85.
• Run Istanbul at Travis CI. Closes #95.
• Update .gitignore. See #85.
• Remove old test directory. See #85.
• Upgrade b-tree to 2.0.0-alpha.9. Closes #94.
• Upgrade twiddle to 2.0.0-alpha.2. Closes #93.
• Upgrade riffle to 2.0.0-alpha.3. Closes #92.
• Upgrade advance to 3.0.0-alpha.2. Closes #91.
• Upgrade twiddle to 2.0.0-alpha.1. Closes #90.
• Upgrade riffle to 2.0.0-alpha.2. Closes #89.
• Upgrade b-tree to 2.0.0-alpha.8. Closes #88.
• Install Istanbul and Codecov at Travis CI. See #84.
• Convert to async/await. Closes #84.
• Build with Node.js 12 only on Travis CI. Closes #87.
• Update LICENSE for 2020. Closes #86.
• Upgrade advance to 2.0.x.

Closes #98.