Add alias slashes

[LKS90]

No description provided.

[LKS90]

I think this edit causes some problems (sometimes deletes not enough).

[DuaelFr]

$separator is not always a slash so I think we should keep the trim() here. But, as it would have been trimmed, we should ensure that the leading char is still a slash before returning $output.

Something like this might be enough:

// If the separator is a slash, we need to re-add the leading slash dropped by the trim function.
if ($separator == '/') {
  $output = '/' . $output;
}
return $output;

[Berdir]

Working a bit on this, can't push to this repository so i'll open a new branch/PR (why can't github fix this...).