This avoid to raise NotImplementedError in _initBTree when _folder_handler
is a string containing, for example 'CMFBTreeFolderHandler'.

This fixes Image.py, which was using _initBTree method.

Also remove assertion on "spec is None", otherwise we have failure (it is used
by portal_caches somewhere).

In case of workflow being a DCWorkflow (from wf_id or workflow_list),
we should get the transition id according to the old DC workflow
transition ids (ex: plan_action and not transition_plan_action).

Before this fix, checking that the action was possible from the
current state was not done correctly (isActionSupported was not
used to set the transition).

Also avoid to check if transition is in getTransitionValueList:
it is useless (transition *is* on of the workflow or is None!)
and calls the expensive 'objectValues' method

This allows to avoid the call of _getWorkflowStateOf if it was already
done before, and so reduce the number of calls of '_getOb' method.

__getattr__ was overriden in order to be able to call the script
using its reference (not prefixed by script_) from another workflow
script (see testTradeReports for example)

the problem is that it was doing a lot of useless getattr (each time,
it was checking for script_foo, even if foo is a transition, state, ...)

we now just change the context given to the script by adding foo
for script_foo to the context dict

It should not be useful with the new WorkflowTool.

by redefining getSourceValue (workflow) and getDestinationValue (transition)

creating a guard when all the informations are already in properties
of the object is useless, these guards were forgotten

in testERP5Workflow, a test was failing due to changes in
storage of expressions (we now store the expression object
so we don't have to recompile the expression all the time)

the only way to escape the 'while 1' loop was depending on changes on the state
variable, which was, before this fix, using the invariant tdef instead of
transition

a few useless methods

in order to remove hardcoded 'transition_' or 'script_'

this file has already been moved to erp5_core