Show effector param scroll bars only when necessary.

Previously the scroll bars were always visible making the forms unusable. It's still the case when there is a lot of content in the field.
This closes #256
allow parameters for restart effector, including children and the machine for SoftwareProcess.restart;
if this model is sensible we might apply it more widely to effectors, to allow parameters to tune behaviour.
(eg for stop, to allow controlling whether it is the machine or just the process which is stopped,
and on start, to allow forcing reinstall)
fix error where collapsed text would leave out interesting messages included with the propagation, with tests
fix failures introduced by dynamic/parametrized RESTART effector; main items are:
    * factory not calling init (deprecate EntityFactory);
    * do{Start,Stop,Restart} methods not getting invoked (deprecated, replaced by pre- and post- start overrides)