Suport for proxy authentication on Proxy Settings or use HTTP_PROXY env variable.

[almusx]

Describe the project you are working on

...

Describe the problem or limitation you are having in your project

The proxy settings dont accept username:password syntax and dont work with HTTP_PROXY environment variable if its set like

http://username:password@proxy:port

Describe the feature / enhancement and how it helps to overcome the problem or limitation

support for proxy authentication for all internet connections redot make like asset lib downloads or android compilation process.

Describe how your proposal will work, with code, pseudo-code, mock-ups, and/or diagrams

...

If this enhancement will not be used often, can it be worked around with a few lines of script?

...

Is there a reason why this should be core and not an add-on in the asset library?

...