v0.2.8

Trackplot web: fastapi update to v0.100.0, caused unexpected 422 error, therefore migrate to flask to reduce requirements and increase stability. Better web help info and layout.
Trackplot cmd: fix layout issue while --show-site
add AppImage files for linux (x86_64) platform, reduce the difficulty of installation and use.
We provide the packed python wheel and tar.gz file, and the built trackplot and trackplot web server in AppImage format.