General tweaks and fixes for Nick's comments.

* Add changes/ files.
* Edit the tor-fw-helper manpage.
* Fix check-spaces.
* Add prototype for get_list_of_ports_to_forward().
* Fix tor_parse_long() TCP port range.
* Improve doc. of tor_check_port_forwarding().
* Check for overflows in tor_check_port_forwarding().
* Demote successful port forwarding to LOG_INFO.

Conflicts:
	src/common/address.c
	src/or/circuitbuild.c