string in import statement is not escaped like regular strings

[sparkprime]

The spec is a bit vague on import, but the BNF clearly says it's a regular string, so it should process escape chars in the same way.

This change could cause grief for people on windows doing import "c:\blah.jsonnet".

On the other hand, the ability to import unicode files with \uXXXX codepoints may be useful.

There is another difference that also does not appear in the spec: You cannot use ||| text blocks in import statements. Either relax that restriction or update the spec.

[benley]

If you can use @"verbatim strings" for import statements, that would take care of windows path backslashes pretty easily.

[sparkprime]

We also have a test for @"something\something" now. When I do the next release, I'll mention in the release notes that @ is now suggested for Windows paths.