Allow initial library to be unindexed

[xogeny]

It should be possible, as with pip, to install something even if it hasn't been indexed by impact, e.g.,

impact install -e git+https://github.com/xogeny/Sensors.git#/path/to/library

The main application for this, that I see, is the ability to load private libraries on GitHub, but I suspect there will be others. Note, this only works for the initial library to be downloaded. Any other libraries have to be indexed (or else impact can't know about them).

If other private libraries are required, then I see two possible options. First, the user could create a private index file (so that impact could find and load additional dependencies). Second, the user could list additional libraries in the install command as a way to preemptively load dependencies that are private.

[xogeny]

Since this is a private repository, the URL will almost certainly require a query parameter with the access token in it, e.g.,

impact install -e git+https://github.com/xogeny/Sensors.git?access_token=...#/path/to/library

[dietmarw]

At the same time one should be able to put the access token in the config file.

[xogeny]

Yes, but the access token in the config file is used when building the index, not when installing.

[dietmarw]

Yes that's why we would need a second (and a third and a fourth ...) one.

[xogeny]

I'm fine with this option, but I think we should put it in a post-conference milestone. Comments?

[dietmarw]

I agree that for the conference we should concentrate to have something user oriented in place (i.e., making released libraries installable). All the developer nice-to-haves should be pushed to after the conference at least.