* temp reasonable state, missing rule_head contents
* better state, with init() and rule_id, but some missing parameters
* performance; embed root in dict; fix lookup
* Add ast_utils
* Fixes related to listnode and typo
* First steps with code gen
* Finalize first steps towards working code generation
* Backwards compat
* Rule execution, error formatting, test cases
* Where rule: support indexing, more expressions, test plane angle measure
* positive length measure test cases
* Venture into entity rules, test actor role
* Fixed for not unary op and address test cases
* Test group qualifier and air terminal type
* typeof() implementation and test annotation curve occ
* Flexible handling of expression, type set intersection, IfcAnnotationSurface test cases
* Functions, derived attrs, fix branch order, allow to terminate branches, apply -1 to index
* Implement express query(), test cases for 2x3 bspline curve
* Function args, if-else, repeat, entity instance construction, cshape test cases
* Multiple function call arguments and other small but influential changes. IfcDotProject() almost working except for variable case
* Make lowercase and fix assignment to qualified lhs
* Entity instance schema without file, aggregate assignment workaround, range fix, lowercase instance locals, extruded area direction test cases
* Enumeration item handling, query() robustness, arbitrary profile test cases
* Empty aggregate_initializer, xor and instance equality, nested expression fix in IfcCrossProduct, axis2-3d test cases
* Numeric stable sort with indices greater then 10, get ast node parent, redeclared derived support, nested expression robustness, define entity functions, case statements, xor, mod, bool literals, nvl, unknown, conversion based unit test cases
* Safeguard for schema name case norm, case norm query variable_id
* free instance comparison, supertype serialization fix, include inherited attributes in locals, proper elif-else in case stmt, loindex, shape rep test cases
* Union operator on set, retain general_aggr_types in parse tree, test cases for property set
* Escape stmt, rule locals and statements
* Return calculated values for redeclared derived attributes
* fix for rules without stmt, add derived and inverse attributes to locals, filter unused locals, wrap exists() arg with lambda to catch indexerror, support repeated aggr init element, typeof() none check, enum namespace uppercase
* Regen 2x3 rules
* Rule test filter only on basename
* Update fixtures for compliance with full body of rules
* Add rule support to ifcopenshell.validate
* Implement usedin() function, test cases for IfcWallSC MLS
* blength
* Run code generation on all schemas
* Try to eliminate runtime pyparsing dep
* Try to eliminate runtime pyparsing dep
* Experimental undo and redo Python prototype
* Simplify history, use transaction jargon, use walk for more robust serialisation
* Black file, set history size, add file reference to entity_instance constructor
* Ensure that files are always passed when entities are wrapped
* Add support for undo/redo of all project module operations
* Minor fix
* Blender to IFC mappings are now managed by Blender RNA, so they don't break on undo operations. See #1475.
* Implement undo for all attribute operations. See #1475.
* Update documentation for installation of add-on
* Revert Blender RNA approach for Blender-IFC mappings, because it didn't scale, but still fix the undo/redo object memory corruption with new "reload_linked_elements" method.
Thomas Krijnen