panwriter version history

Maintenance and minor improvements.

## Checksums ### Windows - PanWriter-Setup-0.8.9.exe sha512: `be/7BjbARqyA3FVaqdG8BKglaxwnhhJZ6jvPVhJfoKcO7IsD6k9jrz81akEthA95I9Zr5pSOcUn7++FvQKZA0w==` ### Linux - PanWriter-0.8.9.AppImage `sha512: GSGz1HhkbC9BAWxG5IwM0uLpt/ZRmo8FPTlLaeDaZMZKRU1G/XWFzdu7OAP8VkouFcPix6Y1hmj8USXBEZFjtw==` ### macOS - PanWriter-0.8.9-arm64-mac.zip sha512: `KGVfSNf9yVA14bjxSpVHU/5uamcuIrLQrdi0K7MqXPgrcIBYYOJUUUplfdCEiY2vQMzUZxfVdGdzKFoQDZZCUg==` - PanWriter-0.8.9-x64-mac.zip sha512: `p+oIWmz0fVew4qOOtpTGCgOGRYKQz1aE6jtKJJmCXq3W1ieWnCdjHM71TdYZCPmx4k8ROPNPrFqHSyM3rCkDSA==` - PanWriter-0.8.9-arm64.dmg sha512: `D1fnz9uUFb/AxuldLSL4OBJSANgbk8rikZ+x15+dSL3uL+RMFxZ8U7mVz7azfTsaet/pwKcVFQXCCxIYNtwckQ==` - PanWriter-0.8.9-x64.dmg sha512: `U5RVCPecj6ik/HekoMCJonIqXU6k/k/46gpC1v4MQuR/tmog8zpl0hHRiFRPrC/HQauyNpu8fRLFhdGjIVaIuQ==`

- [Upgrade to Electron 34](https://github.com/mb21/panwriter/commit/478e5aff3af3528422b338ef7b690e49d88e3d8a) - Export to clipboard: fix md output format name (#184)

Upgraded Electron to 26.2.4

[Major refactorings](https://github.com/mb21/panwriter/pull/57) were done for 0.8.0, which should be a better basis for future work. In the process, one feature was removed: the ability to read user-customizable css files (maybe we can add something like that in the future again, but will have to work with pandoc's [document-css](https://pandoc.org/MANUAL.html#variables-for-html), which we'd need to parse properly).