Revert "Revert "Historically the recator has just called the "async" method of the runner and wheel clients, but this actually creates daemonized processes. In addition to creating a new daemonized process each event, the number of process it creates is unbounded, meaning that the reactor can easily use all available PIDs on a fairly busy master. In addition, there is no bound on the CPU that these are allowed to use (since they can create ALL the pids). This changes the reactor to create a threadpool for executing its master-side clients (runner/wheel). This threadpool has a configurable number of workers (max parallelism) and hwm (max queue size before dropping events).""

This reverts commit 8c7d66d6dc643bfbe4bd7c6e3b64b4630855df8a.
Fix for malformed SLS files crashing reactor

Before if you had a malformed SLS file you'd get something like:

```
Process Reactor-4:
Traceback (most recent call last):
  File "/usr/lib64/python2.6/multiprocessing/process.py", line 232, in _bootstrap
    self.run()
  File "/home/thjackso/src/salt-github/salt/utils/event.py", line 688, in run
    self.call_reactions(chunks)
  File "/home/thjackso/src/salt-github/salt/utils/event.py", line 674, in call_reactions
    self.wrap.run(chunk)
  File "/home/thjackso/src/salt-github/salt/utils/event.py", line 713, in run
    l_fun = getattr(self, low['state'])
TypeError: string indices must be integers, not str
[INFO    ] Process <class 'salt.utils.event.Reactor'> (7656) died with exit status None, restarting...
```

Now you get something like:
```
[ERROR   ] Unable to render reactions for event salt/job/20141204195047408340/new due to errors (['The type broken in runner is not formatted as a dictionary']) in one or more of the sls files (['/tmp/test.sls', '/tmp/test2.sls'])
```
Revert "Revert "Remove "fire_event" from AsyncClientMixin, since this was only added to remove infinite recusion in the reactor-- which is now not calling this API""

This reverts commit ba7f08d047afffc2b87950910cac0cdd48b76302.
Revert "Revert "Remove some un-used variables""

This reverts commit 82b5567c9248f345e2b388e3d238d51b7a0d9640.
Revert "Revert "Pylint cleanup for threadpool""

This reverts commit 32d01ee6c6bd4a7070be158c7188ede14cb34b60.
Don't run 'exec_action' blindly.
Fix jinja search path for local file_client

Now that FS backends other than roots work with a local file_client,
there is no need to look only in the file_roots directories.

Fixes #17963.
Add support for 'parameter' where appropriate.
Only return cleaned-up module names.

- strip module descriptions
- strip indentation from list output
- strip internal modules (help, usage, version)
Strip additional output from targets, return only actual targets.
Added 'parameter' to CLI examples.
Deprecate 'parameter' in favour of 'module_parameter'/'action_parameter'.

A generic 'parameter' argument doesn't cover what's actually required.
In some cases, parameters need to be passed either to the executed
module, action or both.

This changes gracefully deprecate the old 'parameter'.
Handle 'target' + 'action_parameter' in 'set_target()' correctly.
Documentation improvements for get_modules() and get_target_list().
Be a bit more careful with the results of 'exec_action()' and also sanitize them a bit.

In case the 'exec_action()' call for 'get_target_list()' returned no
results, because there were no available targets, the module would
stacktrace.
Documentation improvements for 'get_current_target()'.
Handle '(unset)' as return value (when no target is set) in get_current_target().
Documentation improvements for 'set_target()'.
Documentation improvements for 'exec_action()'.
Don't try to run blindly non-existent modules.