Comment-only changes to tor

My branch comments-20151204 contains comment-only changes to Tor:

get_connection_array no longer takes "n"
Move a comment in router_get_my_descriptor to the correct line
Update comment for connection_connect
- port is in host order, addr is a tor_addr_t so endianness is abstracted
- addr and port can be different from conn->addr and conn->port for proxies
connection_get_by_type_addr_port_purpose also ignores connections that are marked for close