Fixed URL decode on Windows

[roovio]

l:encoded_path does not contain ':' so regexp match will fail and substitute() never called. The end result thus would still be '/C:/foo/bar' that the initial code presumably wanted to fix.

[w0rp]

I don't think this is right. I think file:///C%3A/foo/bar/baz.tst should be converted to /C:/foo/bar/baz.tst. Otherwise it's not possible to represent /C:/foo in Linux.

[roovio]

At the moment GoToDefinition is broken on Windows because /C:/foo/bar is not a valid file (vim creates an empty buffer).
Judging by the comment the initial code was there to exactly adress this issue:

    " If the path is like /C:/foo/bar, it should be C:\foo\bar instead.

If we want to have equally supported /C:/foo/bar on Linux and C:\foo\bar on Windows then the URL decoder might need to have additional platform checks.

[w0rp]

The URI received should be file:///C:/foo/bar/baz.tst, which will be translated to C:\foo\bar\baz.tst. The colon in the URI must not be encoded.

[roovio]

With ccls I am receiving file:///C%3A/Users/....
Checked by hacking into ale#definition#HandleLSPResponse l:item.uri

[w0rp]

Open a bug for that project and get them to output URIs with the colon in them. They shouldn't be encoding the colon in the drive letter part of the path.

[roovio]

Ok thanks

[w0rp]

On second thought, I'll just accept it and add a platform check. They should still output a colon without encoding it.

[w0rp]

Done.