Hpl-specs

Added
- `get_conjuncts(p: HplPredicate | HplExpression)` function to `hpl.rewrite` module.
- `get_disjuncts(p: HplPredicate | HplExpression)` function to `hpl.rewrite` module.

Changed
- Small improvement in `hpl.rewrite.simplify`.

Added
- `split_and(p: HplPredicate | HplExpression)` function to `hpl.rewrite` module.
- `simplify(p: HplPredicate | HplExpression)` function to `hpl.rewrite` module.
- `is_inclusion` and `is_comparison` properties to `BinaryOperatorDefinition`.
- Factory functions `boolean`, `number` and `string` to `HplLiteral`.

Changed
- Small optimization to `HplExpression` type checking system.

Fixed
- `HplPredicateExpression.expression` is now cast to `DataType.BOOL` on construction.

Added
- `canonical_form(property: HplProperty)` function to `hpl.rewrite` module.

Changed
- `HplAstObject.but()` returns the same object if no attributes would change.

Fixed
- Sanity error when creating some types of predicates that was too strict.

Fixed
- Exception when parsing specifications.

Added
- `hpl` CLI script to test file/property parsing