Expect dependencies in same directory to prevent accidental name clashes

[ThomasMader]

I think that it's better to expect the dependency dirs inside the tools directory because it's the only place you can be sure of no problems with the outside world. #250 (comment)

See also #250 (comment) and following comments.

[dlang-bot]

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[CyberShadow]

The problem you're trying to solve has workarounds and several solutions, of which this isn't a good one. This will break things for users, and overall not an improvement. See https://github.com/dlang/tools/pull/250/files#r160042841.

[ThomasMader]

Yes I came to the realization that it's too much of a cometic change with no real value but much outside noise to be worth it at all.
Thanks.