Change '/' to path.sep.

[be5invis]

Potential fix of #92.

[zjhmale]

@be5invis After playing around our extension on windows7 and windows10, I finally figure out the reason under the hood, it is nothing related to the path separator, one wired thing of VSCode RTS on windows is that, e.g.

let [dpath, module] = uri.split(innerCompilerOptions.src)
// module now is "\\TermLang\\Unify.idr"
let moduleParts = module.split(path.sep)
// moduleParts is ["\\TermLang\\Unify.idr"] which should be ["\\", "TermLang", "Unify.idr"] as expected

which is really confusing, but we can do the split(path.sep) in a normal nodejs prompt on windows.

Anyway, I got a final solusion to fix this without any annoying path splitting and joining.

[be5invis]

@zjhmale this fixes the issue on mu machine that :l ends up with empty string.

[be5invis]

@zjhmale what's the result of path.sep.

[zjhmale]

@be5invis the result of path.sep is "\"

[zjhmale]

And #65 is causing when user start an REPL with single Idris file instead of an ipkg project.

[zjhmale]

Thanks!