Add deprecation warning where needed

[degremont]

A couple of method and classes are deprecated in ClusterShell. We need to add call to warnings.warn where needed.

The next release will be able to drop this code.

[degremont]

Partially done by #271

[thiell]

What remaining methods/classes have to be deprecated in 1.8?

[degremont]

Maybe current code is enough, I'm listing some deprecated features here:

• Already done?

  • Worker.last_*() (1.6)

• Don't know how to do with symbol/aliases

  • NodeSet.STD_GROUP_RESOLVER (1.5)
  • NodeSet.NOGROUP_RESOLVER (1.5)
  • WorkerBadArgumentError (1.4)

• TODO

  • topology.conf: Main section (1.7)
  • GroupResolver.set_verbosity() (1.7)

• Not yet

  • WorkerSimple (1.7, still used by WorkerOpen (as of 1.8))
  • Old EventHandler prototypes (1.8)

[thiell]

Thx. Sounds good to me.

I say we remove the first two in 2.0.

There is no rush for the TODO items. Let's do that later.

Let's work on getting rid of WorkerSimple in 1.9 as much as possible, so we can remove it in 2.0.

[thiell]

• removed all Worker.last_*() methods in #495
• added deprecation warnings when old EventHandler method signatures are still used in #358
• deprecating Worker.current_* in the documentation also in #358