Add option to use real names for emails (per network).

[wwiv]

Each network should have a setting to use real names for netmails.

This would be useful for FIdoNET where handles aren't allowed.

[wwiv]

From #1236

Then when parsing email by name, the network can use it's preference to decide which to prefer. 
Right now in email.cpp we iterate through all handles looking for a match. If not match is found
 then iterate through all real names, using the first matching real name.