Shougo

The original API `virtualtext()` cannot be extended. But this API can be added the following opts. `winid`, `mode`, `inclusive`

> I think we should explicitly allow for a blockmode option therefore Well, I should add the argument?

I think `opt` argument should be added in the next PR. But I will add explicit selection mode.

I have added the argument.

> Memory leak Fixed.

I have added tests.

> On the other hand, I point out that the function name is inappropriate: the name filecopy, with file being singular and prefixed with file, suggests that only one file...

Almost tests are passed. But I don't know how to fix the CodeQL error. The original routine is already exists...

I don't want to create both `filecopy()` and `dircopy()`.

The functions like `getftype()` works for both file and directory.