Add an option for Google scholar baseurl

[Izumiko]

It is difficult to access Google scholar without a proxy in China, so could you add an option to set the baseurl of Google scholar with a mirror site or to use an HTTP proxy to access Google scholar?

[nico-zck]

Would you provide some reliable mirror sites?
In general, if you can use some proxy tools properly, they will automatically take over the system proxy and make Google services available.

[Izumiko]

Mirror sites die frequently, so it is hard to choose a reliable one. I think an option like zotero-scihub will be better, which let the users set their usable mirror.
Besides, using proxy tools to take over the system proxy will add complexity to the network, I prefer setting the proxy inside each program other than system-wide.

[nico-zck]

I will consider adding a preference option to Zotero in the future.
And I think it makes more sense to suggest Zotero to support an application-level proxy.