Python API documentation generation tool Code

- Fixed minor bug in handling of markup like `foo <bar>`

- Added "--inheritance hidden" to not list inherited vars at all.

- Use 'show_private' option to specify whether to show/hide private vars.

NOTE: This changes the default behavior of that latex writer.
Previously, it hid private vars by default; now it will show
them by default.

- If we're using introspection, then import everything that we plan to
document before we start introspecting anything. This can be important
if one module modifies another. The bug that inspired this fix was
sf bug #1896919.

- Fixed typo in error message

- When constructing UML graph nodes, guard against the case where
class_doc.sorted_variables is UNKNOWN. This is known to happen
if the user defines a class that subclasses from an undocumented
class that itself has a nested class. E.g., Tkinter.Misc.getint.

- In mro calculation: if there's an inconsistent base class hierarchy,
then print an error and recover using depth first search.

- Display more useful error message when '--graph' gets something
unexpected.

- refactored class_tree_graph & uml_class_tree_graph -- now they share
most of their code.
- added truncation when class graphs get too big: max_subclass_depth
truncates subclasses that are too far down in the tree, and
max_subclasses limits the number of subclasses that are shown for
any given class.
- undocumented base classes are now drawn with a grey background
- uml graph options:
- Changed default values for max_attributes & max_operations
- Added options to control whether parameter defaults are shown;
and to truncate signatures that are too long
- set minimum width for uml nodes to 100
- Fixed bug in DotGraphNode -- subclasses should share the same
_next_id var, not use their own.
- If dot fails & epydoc.DEBUG is true, then print the broken dotfile
to a temp file.

- Always write the subclass list, even if the class tree is drawn.
I plan to truncate large class diagrams, so the list will be
useful in those cases.