* Add TypedValue::instant(micros).
* Add From<f64> for TypedValue.
* Add lookup_values_for_attribute to Conn.
* Add q_explain to Queryable.
* Expose an iterator over FindSpec's columns.
* Export edn from mentat crate. Export QueryExecutionResult.
* Implement Display for Variable and Element.
* Introduce a `kw` macro.
This allows you to write:
```rust
kw!(:foo/bar)
```
instead of
```rust
NamespacedKeyword::new("foo", "bar")
```
… and it's more efficient, too.
Add `mentat::open`, eliminate use of `mentat_db` in some places.
* Test the mentat_query directory on Travis.
* Export common types from edn.
This allows you to write
use edn::{PlainSymbol,Keyword};
instead of
use edn:🔣:{PlainSymbol,Keyword};
* Add an edn::Value::is_keyword predicate.
* Clean up query, preparing for query-parser.
* Make EDN keywords and symbols take Into<String> arguments.
* Implement parsing of simple :find lists.
* Rustfmt query-parser. Split find and query.
* Review comment: values_to_variables now returns a NotAVariableError on failure.
* Review comment: rename gimme to to_parsed_value.
* Review comment: add comments.
