Add airways parsing (+ a few other tweaks)

[philsjh]

First contribution!

• Add airway parsing to the SCT parser.
• Expand the matching in the pest parser to accommodate this
• Expand the parser to allow inline sct comments
• Alter parsing flow to parse independent parts of the sector file first, then re-parse for anything that depends on other parts of the sector file (for example: Airways can have fixes, VORs, or NDBs, but we don't know if the fixes are legit if we can't check).
• Update test cases to support new functionality

I'm not as familiar with rust as I am with other languages, so comments/opinions are welcome!

[globin]

Sorry for taking so long to respond to this, I had to think a while which approach I'd like to take with this. I believe this pull request inadvertently brings up a larger decision, namely if we should validate and ensure consistency while parsing.

I have ignored consistency so far as up to now these checks would have needed sct data in addition to parsing ES topsky maps and additionally a lot of files I have tested actually are inconsistent.

For the sector file parsing I'd prefer keeping this approach as this also reduces complexity by quite a bit. I've pushed what I'd propose to https://github.com/blip-radar/vatsim-parser/compare/sct-airways. This uses the Location enum (Fix or Coordinate) which I had previously already used for ES topsky maps.

All that being said, I do believe that checking consistency is a valid concern and should be implemented here, but decoupled from the parsing logic. Issue to keep track of this in #18.

Are there any issues I have missed in my rambling?

[philsjh]

Hey Robin,

No problem, yeah I think that all makes a lot of sense, and using a location enum is probably best.

@caspianmerlin might have a further opinion on this.

Cheers,
Phil