FTP protocol support

Implementation of ftp protocol.

Fixes #1672

Signed-off-by: Lukasz Marek <lukasz.m.luki@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/allformats.c

@@ -313,6 +313,7 @@ void av_register_all(void)
     REGISTER_PROTOCOL(FFRTMPCRYPT,      ffrtmpcrypt);
     REGISTER_PROTOCOL(FFRTMPHTTP,       ffrtmphttp);
     REGISTER_PROTOCOL(FILE,             file);
+    REGISTER_PROTOCOL(FTP,              ftp);
     REGISTER_PROTOCOL(GOPHER,           gopher);
     REGISTER_PROTOCOL(HLS,              hls);
     REGISTER_PROTOCOL(HTTP,             http);