Definitions section – Clarifications – some structural changes

[thedoctor]

Hey guys,

Sorry for the poor packaging of this PR, it's pretty bulky and touches a lot of stuff. Also I just noticed the changelog stuff today, so I'll have to add quite a few entries there, but I figured it'd be worth submitting this first so the changes can be reviewed.

In this PR, main changes:

• Slight modifications to the way aspects were being loaded into the aspects page to eliminate some redundancy.
• Pipe the data loaded from _data/aspects through markdown to allow for internal links.
• Add a Definitions section and a bunch of definitions for terms that either I thought needed clarification for the purposes of the spec, or might be obscure to uninformed readers. Several definitions are stubs, and all should be reviewed to make sure I didn't write anything controversial or ridiculous (or wrong) – they have edit/discussion links for convenience. Also, I tagged the first occurrence of each defined term in each section with a link. (There is a minor hack in 1_aspects.html to get these to display properly)
• Formatting (normalized indentation, swapped out smart-quotes where I saw them, and removed trailing whitespace)
• Added hyperlinks where possible to external resources (RFCs, NIST pubs, etc)
• Actual clarifications to the level requirements. Most notable changes include
  • the definition of 'actor' and a note about backups in 101-KeySeedGeneration
  • a clearer distinction between 'wallet' and 'address' in 102-WalletCreation
  • clarification of to whom backup requirements apply in 103-KeyStorage
  • clarification of multi-factor authentication requirements in 104-KeyUsage (I removed the requirement of a username/password combination and generalized to requiring an identifier (username, email) and then the previous number + 1 authentication factors.)

[Abstrct]

I'm still working on taking in all the changes but I just wanted to quickly say thank you. This is an awesome contribution and I look forward to hitting that inviting green button up there.

Since there are a mix of changes to the repository/page, and changes to the standard itself, I will hold off to give everyone a chance to comment.