Proxy support

[Makman2]

Hi :)

I tried to install an lpf package (mscore-fonts) from inside my university net that sits behind a proxy. It appears that this is the issue, as downloading the sources is the step that fails during package approval. On my home net it works without problems.

It would be nice if lpf would honor the standard environment variables (https_proxy / http_proxy) to support connections behind a proxy.