Open API interface to families.

Object Family Terminology
-------------------------

Family table - A table which describes various attributes of an
object. Each row in the table is called a family member. Each family
member defines a set of attribute values(represented by text) for the
attributes in the object family.

Family member instance - An object, which when created, applies a set
of attribute values to the attributes in the object family.

Family - The family table and family member instances.
The routines in this file allow you to:
. add a family member
. query attribute data, class count, class data, class name,
family data, instance data, member column data, or member
row data.
. check attribute status, family status, or member status.
. create an attribute or a family.
. delete an instance or a member.
. edit an attribute, a family or a member.
. evaluate intent data.
. free attribute data, class data, family data, or member data.

Terminology:
-----------
part family - a set of parts defined by a template part,
table of attributes, and family members.
Also referred to as a family of parts.
template part - A part file that contains a table of the
family members and attributes
(parameters) associated with each
member of a part family.
family member - is a part file which belongs to a part
family and is enumerated in the template
part's table of members and attributes.
family attribute class - is a subtype of a family attribute such as
a character string, expression, etc. See
the description for the "subtype" field in
the structure UF_FAM_class_data_s.

Concepts:
--------
A family is defined by a set of family attributes and a table of family
members which define the values of the attributes. For example the
following family has two attributes. The first attribute is a name
attribute. The second attribute is an expression attribute. A part file
containing a family is known as a family template part.

NAME P1
member1 1.0
member2 2.0
member3 3.0

By creating an instance of a family member at the UF_FAM level, the
attribute values of that member are applied to the template part. In
the example above, you would set the value of the NX expression P1
to 2.0 in order to create an instance of member2.

If you create an instance of a family member at the UF_PART level,
you are creating an instance of the member inside of a new part which
is a copy of the template part. The new part inherits the name of the
member name, e.g. in this case it would be called member2.prt.

At the UF_FAM level, a family member select intent is a set of rules
which allow the system to automatically select a family member from
a family. Using the example above, an intent might look like "P1 >
1.0" or "P1 == 3.0" or "NAME == member3".

At the UF_ASSEM level, an instance intent is a UF_FAM intent rule
associated with an assembly instance. This allows the system to
automatically select a new part family member based upon the rules
which specify the member selection intent.