more comments, added an assertion
comment about plans
Merge branch 'devel' into newids
- minor bugfixes
- reworked make_id, adding separate dict_id and _dict_id methods.  The idea is that a child
class will define its own dict_id method, as a way to standardize the formation of ids for
that class.  Note also that the dict_id method is a @classmethod, so that you can form a
suitable id without having an object, you just need to know what class you want.  This
feature is essential because it lets you compute an id and use it to get an object from a
dictionary.
Add a dict_id method (c.f. id.py) for class derived_var.
Fix up id initialization.
Add a dict_id method (c.f. id.py for what this is about).
Add an abbreviation rv for class reduced_variable (btw I did that for derived_var too).
The reason for the abbreviation is that sometimes reduced_variable definitions have been
getting to wordy to see what's going on.
Put an upper bound on output of the filetable.__repr__() method.
Add debugging output.  This is temporary (thus marked with "jfp"), but I'll keep it for a while.
It's a reminder of some obsolete constructs which I can probably rip out soon.
In AMWG plot set 4, rework the ID settings to use the new dict_id method; and a bit more cleanup.
In plot set 4, constructing reduced_variables dict: no need to construct a reduced variable's id
twice!  First make the reduced variables, then use their ids as dict keys.