Support 4.x graphviz format 2

[aothms]

Sorry for the three reverts, I accidentally started off from an old branch point and quickest was to revert and reapply on top due to the large refactoring commit.

[Ghesselink]

Nice :) I tested it on models in validate and found a couple of small errors (incl fixes)

see also
https://github.com/opensourceBIM/python-mvdxml/pull/21/changes

1. _parse_mvdxml_token rejects unquoted parameter values.
Every value goes through ast.literal_eval, accepting python literals but mvdXML writes them unquoted, so ContextType[Value]=Model raises ValueError: malformed node or string on line 1: <ast.Name object> and CRSName[Value]=EPSG:5555 raises SyntaxError. There are 419 of them in ReferenceView_V1-2.mvdxml, and one of them takes down its whole concept. fix would be to to fall back to the stripped string,

2. validate() selects expressions one level too shallow.
[value[0] for value in self.rules()] assumes a flat list, but parse_template_rules isn't.. That gives TypeError: 'node' object is not iterable, IndexError: tuple index out of range on an empty group, and drops every ;-separated expression after the first: 16 checks skipped were skipped with 9 concepts (in ReferenceView_V1-2).

**3. [Type] assumes an ifcopenshell entity.instance **
is_a() doesn't have a type checkt, so str resulted in AttributeError: 'str' object has no attribute 'is_a'.fixed by using isinstance(item, ifcopenshell.entity_instance) first.

4. The graphviz test fixture cannot construct an instance.
It subclasses entity_instance, whose __setattr__/__getattr__ go through wrapped_data and a recursive without the underlying C++ class went on forever: RecursionError: maximum recursion depth exceeded. fix is to use a Mock spec'd on entity_instance

##tests

Running ReferenceView_V1-2 end-to-end, concepts that crash:

model	concepts run	crashing before	after
Molio_with_URIs.ifc	144	46	0
DuplexHouse_Heating_RME.ifc	96	28	0
Duplex_MEP.ifc	80	14	0

[Ghesselink]

Nice :) I tested it on models in validate and found a couple of small errors (incl fixes)

see also
https://github.com/opensourceBIM/python-mvdxml/pull/21/changes

Is it OK to merge into support-4.x-graphviz-format-2?

1. _parse_mvdxml_token rejects unquoted parameter values.
Every value goes through ast.literal_eval, accepting python literals but mvdXML writes them unquoted, so ContextType[Value]=Model raises ValueError: malformed node or string on line 1: <ast.Name object> and CRSName[Value]=EPSG:5555 raises SyntaxError. There are 419 of them in ReferenceView_V1-2.mvdxml, and one of them takes down its whole concept. fix would be to to fall back to the stripped string,

2. validate() selects expressions one level too shallow.
[value[0] for value in self.rules()] assumes a flat list, but parse_template_rules isn't.. That gives TypeError: 'node' object is not iterable, IndexError: tuple index out of range on an empty group, and drops every ;-separated expression after the first: 16 checks skipped were skipped with 9 concepts (in ReferenceView_V1-2).

**3. [Type] assumes an ifcopenshell entity.instance **
is_a() doesn't have a type checkt, so str resulted in AttributeError: 'str' object has no attribute 'is_a'.fixed by using isinstance(item, ifcopenshell.entity_instance) first.

4. The graphviz test fixture cannot construct an instance.
It subclasses entity_instance, whose __setattr__/__getattr__ go through wrapped_data and a recursive without the underlying C++ class went on forever: RecursionError: maximum recursion depth exceeded. fix is to use a Mock spec'd on entity_instance

##tests

Running ReferenceView_V1-2 end-to-end, concepts that crash:

model	concepts run	crashing before	after
Molio_with_URIs.ifc)	144	46	0
DuplexHouse_Heating_RME.ifc	96	28	0
Duplex_MEP.ifc	80	14	0