replace fake header with FST-1027 - Beta 013

[matthid]

See #1768

I decided to support `#r "paket:". As we use the FCS-Tokenizer multi-line strings and similar things work.
In fact

#r "paket:
storage: none
source https://nuget.org/api/v2
source ../../../nuget/dotnetcore
 
nuget Fake.Core.Target prerelease
nuget FSharp.Core prerelease"

Looks quite nice.

As this currently prints

E:\Projects\faketest\myscript.fsx (1,0)-(6,31): Warning FS0213: 'paket:
storage: none
source https://api.nuget.org/v3/index.json

nuget Fake.Core.Target prerelease
nuget Fake.Net.Http prerelease' is not a valid assembly name

The natural way to do it is:

#if FAKE_DEPENDENCIES
#r "paket:
storage: none
source https://nuget.org/api/v2
source ../../../nuget/dotnetcore
 
nuget Fake.Core.Target prerelease
nuget FSharp.Core prerelease"
#endif

Another way would be to disable warning FS0213 (at least for strings starting with paket: )

[matthid]

Even better: As this thing is a warning only we can ignore that.

Maybe I can get @Krzysztof-Cieslak or @enricosada to remove this warning from Ionide as well (or even better provide intellisense within the paket: string...)

Now

#r "paket:
storage: none
source https://nuget.org/api/v2
source ../../../nuget/dotnetcore
 
nuget Fake.Core.Target prerelease
nuget FSharp.Core prerelease"

works without warning. Now I'll try to get the defaults right, such that storage:none and the NuGet default source is not required (only when no other source is given)

[Krzysztof-Cieslak]

Both disabling warning in this particular case, and providing intellisense inside those strings should be doable and not too complex.

[matthid]

Now we get

#r "paket:
nuget Fake.Core.Target prerelease
nuget FSharp.Core prerelease"

Because we default to storage:none and the default NuGet source.

[matthid]

Ok if any string is given in #r "paket: <data>" and <data> is by accident a valid filename, the compiler will emit error FS0078 instead of a warning:

C:\projects\fake-6w516\integrationtests\core-use-external-paket-dependencies\temp\use_external_dependencies.fsx (1,0)-(1,25): Error FS0078: Unable to find the file 'paket: groupref Main' in any of

I hope the workaround is to use #r "paket: <data> // and paket allows in-line comments.