qt: handle non-`text/uri-list` multi-line text drop properly
A single URL can not contain multiple lines. If the input is multi-line text, then it should be treated as multiple urls, not a single url.
This is with accordance to text/uri-list
, the main difference
is being more relaxed regarding the line ending. Unlike
text/uri-list
, CRLF line ending is not mandatory and LF is
enough.
Request review @chub.