move "view_graph" view from erp5_workflow bt5 to erp5_graph_editor

after calling this script, positions of the states will be chosen by jsplumb
and manually saved positions will be erased

+ separate python script from XML

to ERP5 Workflow and use them

they are used in Interactions
+ improve categories TALES

instead of getXXXScriptIdList, which calls getXXXScriptValueList anyway (-> bad performances)

instead of using self.publish()

it was the same as PythonScript property sheet

guard expression is now an Expression object, so it is required to
display its 'text' attribute

it was 'TypeError: cannot concatenate str and NoneType objects'

and modify checkGuard to have expected behaviour

this fixes error when accessing to special views on Transition objects
it also remove duplication of guard properties (they were stored in the
properties of the guarded object *and* in a guard object)

portal type Variable was renamed to Workflow Variable

remove InteractionWorkflow property sheet