* Rename `#_q` to `#_l` (for literal)
* Add `#_i` method for creating identifier

0.5 2019-01-25
--------------

* Implement query combination: `union`, `intersect`, `except`
* Implement `#not_in` method
* Implement case expression (using `#cond`)
* Implement not in expression
* Implement in operator
* Implement cast operator (using either `#cast` or `#^`)

0.4 2019-01-21
--------------

* Implement query mutation
* Can now use `!` as `not` operator
* Clauses as real expressions
* Implement context injection
* Refactor and simplify code

0.1 2019-01-16
--------------

* First working version