* Part 1: define ValueTypeSet.
We're going to use this instead of `HashSet<ValueType>` so that we can clearly express
the empty set and the set of all types, and also to encapsulate a switch to `EnumSet`."
* Part 2: use ValueTypeSet.
* Part 3: fix type expansion.
* Part 4: add a test for type extraction from nested `or`.
* Review comments.
* Review comments: simplify ValueTypeSet.
* Part 1 - Create as_edn_value function.
* Do not include defaults inside output.
* Pretty-printed by default. Do we want to make that a flag?
* Includes simple test just to make sure it works.
* Part 2 - only include ident if available.
* Part 3 - Remove spacing and newlines as unnecessary.
* Update function to build edn::Value directly rather than parsing from string
* Update test to actually test the functionality.
* Address review comments ncalexan.
* Rename `as_edn_value` to `to_edn_value`.
* Move `db/src/values.rs` to `core/src/values.rs` so we can reference inside `core/src/ib.rs`.
* Add `lazy-static` crate to core `Cargo.toml`
* Expose `values` as a public module from `core`.
* Update references to values in `db/src/bootstrap.rs` & `db/src/lib.rs`.
* Add new static vars for `DB_FULLTEXT`, `DB_INDEX` & `DB_IS_COMPONENT`.
* Use static vars exposed in `values` inside `to_edn_value`.
* Remove `db/id` as key in attribute output and use `entid` as `db/ident` if no `ident` is found for that `entid`.
* Update test to match new expected output.
* Add doc comment for function
* Address review comments ncalexan.
* Update function docstring to give clearer description of function.
* Do not all entid at all to output.
* Clean up code fetching ident (make it rustier).
* Address review comments rnewman.
* Extract out to new `to_edn_value` functions code for creating `edn::Value`\'s for `ValueType` and `Attribute`.
* Use `map()` to create schema edn value rather than a loop.
* Address review comments rnewman.
* pass cloned instance of ident to `Attribute::get_edn_value`.
* update `use` import for `edn`.
* remove unnecessary call when using ident as key on `associate_ident`.
* Fixed bug whereby we didn't differentiate between `db.index/value` and `db.index/identity` when generating `edn::Value`
* Add extra assert at the end to ensure we get the same output when we convert the same schema to edn multiple times
* Move check for type of uniqueness to `match` statement.
* Also use `iter` instead of `into_iter` when iterating schema map.