Fix dropping files with '#' in name

[jeremypw]

Fixes #876

Dropped uris were being sanitized by creating a file from them and then obtaining the path but this seems unnecessary and was causing truncation.

[Marukesu]

If the external application is sending files URIs, then he should be escaping those '#' in the filename as it denotes the start of the fragment part of the URI.

[Marukesu]

If the external application is sending files URIs, then he should be escaping those '#' in the filename as it denotes the start of the fragment part of the URI.

That being said, I don't think we should be removing the scheme as the code implies it does. We don't know the intent of those URIs. Even in the 'file://' case, we don't know if they are local or not.

[jeremypw]

@Marukesu Could you raise a separate issue if there is a demonstrable downside to removing the "file://" scheme? This PR does not affect that behaviour.

As far as I can tell Terminal only uses dropped files as files if they are dropped on the "Add Tab" button. Dropping on the Terminal widget just converts to text. I considered removing URILIST target type but although that works you then get paste warnings.

[jeremypw]

Closing in favor of #894 for now. This PR also fixes dropping with Files but that should be fixed in Files.