Resolves #174 with the following changes:

  1 - Side-mounted engines now can 'see' fuel through their surface mounts.
  2 - Now detects when an attachment can't carry fuel (attachment is strut)
  3 - Now traverses yellow fuel lines to find fuel.
I had originally thought it would be possible to encapsulate all the problems in this one call, returning a true list of all the attachnodes....
...and then I found out that fuel lines aren't even attachnodes at all... and suddenly that approach became less plausible.