Handle `.jl` in name?

[00vareladavid]

Someone tried to add a package with Pkg.add("Foo.jl"). This seems like a reasonable mistake for a beginner to make.

We can detect this case and remove the extension automatically. This is not too magic because the original string can never be a valid package name in the first place.

[fredrikekre]

Maybe an informative error message: Did you mean Foo instead of Foo.jl is better than to do things magically?

[StefanKarpinski]

I'd favor just handling it. I tried early on to only use the .jl extension in places where it was needed to identify something as a Julia package, but that didn't work out. In this case, it's not like Foo.jl is a valid package name, so I don't see the harm in just making it work.

[KristofferC]

This is now handled automatically in REPL mode and gives a good error message in API mode.