Cardano Updates

* move Everything file, minor README tweaks

* moved Everything to index and set layout

* ToC

* added links to subsections in index

* intro in index

* index:types

* switched Type stuff to .lagda.md, variable generalising, removing unneeded code

* update README + gen vars in Type.RenamingSubstitution

* type ren/sub cleanup and knockon effects

* type eq cleanup

+ small cleanup in type ren/sub

* type reduction cleanup

* added CK machine for types to the index and cleaned it up

* removing a closure style CEK machine for types which isn't used.

* added some explanation of the CK machine for types

* builtin + declarative syntax

* moving builtin postulates into Builtin and updating builtins generally

* Declarative renaming and substitution

* decl erasure and examples

* reverting to lazy bytestring in main

* moving some utils into utils

* simplified the type signatures in Decl Ren/Sub

First attempt at an interface module for the ledger team.

I had to do a lot of moving becuase we want the dependencies of this
package to be as minimal as possible, in particular we really don't want
it to depend on the plugin (which `plutus-ledger` does), or things like
`servant` or `iots-export`.

quick and dirty for now

* Update Option.hs

* fix

* fix

* trigger build

* fix unexpected hex