Add Exit Port Policy graph

To get an ExitFlag, a relay need exit to only Ports 80 & 443. Basically, metrics answer how many Exit Nodes will my Tor Browser possibly use for now. Add Exit Port graphed by Consensus Weight and relay count.

This will help us answer questions like:

How many Exit Relays use ReducedExitPolicy?

• How many Exit Relays may will my Port 25, 465, 587, 110, 143, 993, 995 E-Mail Circuits choose to use from?
• How many Exit Relays may will my Port 6667 & 6697 IRC Circuits choose to use from?
• How many Exit Relays may will my Port 22 SSH Circuits choose to use from? ... DNS (53), FTP (21) ...

Per Country? Per IP 4&6 Version?

User can learn if all of his connections to special service port will go over only low fraction of Exit or like for web traffic over large set of ExitRelays.