bad enough to almost make socks proxies with multi interface unusable

  If the CURLOPT_PORT option is used on an FTP URL like
  "ftp://example.com/file;type=A" the ";type=A" is stripped off.

  I added test case 562 to verify, only to find out that I couldn't repeat
  this bug so I hereby consider it not a bug anymore!

  I've now made TFTP "connections" not being kept for re-use within libcurl.
  TFTP is UDP-based so the benefit was really low (if even existing) to begin
  with so instead of tracking down to fix this problem we instead removed the
  re-use. I also enabled test case 1099 that I wrote a few days ago to verify
  that this change fixes the reported problem.