Installer of new GUI. Feel free to report any issues. Read Installation_cn.md or Installation_en.md, double click alas.exe to install and run.

Adds:

• CTRL+R and CTRL+SHIFT+R to refresh.
• Installer self-updating, but webapp still unable.

Fixes:

• Electron loaded before Alas backend prepared.
• Unable to slash if not having a commit. ( #650 )
• Pypi still uses proxy when pypi mirror is defined.