Fixes#2430.
When removing a torrent, try to remove config filenames under both old
and new filename formats. This prevents torrents from being incorrectly
re-added when old-format files aren't removed.
* refactor: include <memory> when using shared_ptr or unique_ptr
* refactor: include <cstdio> iff we use it
* refactor: include <cstring> iff we use it
* refactor: include <cstdlib> iff we use it
* refactor: include <string_view> or <string> iff we use it
* refactor: include <array> iff we use it
* refactor: include <ctime> iff we use it
* refactor: include <cctype> iff we use it
* refactor: misc #include cleanups in libtransmission
* refactor: add tr_torrent_metainfo class
Can be used for parsing bencoded .torrent data without instantiating
a tr_torrent. This will be used in all the places where client code
needs to test a .torrent file for validity / to add a preview window
before adding the torrent.
