Compiles under Windows, switches to 1.3.1

Also performs the following updates:
  Removes all warnings with -Wall -Wconversion -Wshadow
  Removes src/tcprelay.c.orig and src/tcprelay.c.rej
  Updates manual (doc/tcprelay.1) with connexe option
  Creates src/test-connexe.{sh, cmd} scripts to test --connexe