Solved empty goal parsing bug

Solved a bug that occurred when parsing a goal composed of an empty and formula:

(:goal (and))

Solved parsing bug

Solved a bug that occurred when parsing problems whose goal contained a single atom.

Support for modifying the problem and dumping it in PDDL

This release only contains some minimal, incremental changes:

• Support for changing the current state of the problem
• Methods for obtaining the names, types and indexes of objects
• A method for obtaining the PDDL encoding of the entire problem

Support for negative preconditions

Added limited support for negative preconditions, i.e., negated atoms in action preconditions.

Support for existential preconditions.

Added support for existential preconditions, i.e., exists keyword in action preconditions.

Initial release

Initial version (1.0.1) of the package. See https://pypi.org/project/lifted-pddl/1.0.1