Request more compression formats support

[OriginStar-Xpp]

It can't install my singer package in some file formats like ".7z"

[oxygen-dioxide]

I (as a developer) have tried to add .7z support, but the performance is bad. Due to the design of 7z format, OpenUtau has to read through the whole 7z archive to access a certain file, while for .zip and .rar it only has to read a small part of the archive where the file we need is located. So we decided not to officially support 7z in OpenUtau.
(Actually you can rename .7z to .zip and it will install on OpenUtau, but very slowly)