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.
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 sockstat on FreeBSD as an alternative to lsof
Fix lint
Populate the 'virtual' grain on OpenStack FreeBSD systems
Fix jinja tests

These tests were using the now-outdated method of looking in the
file_roots for cached templates in masterless mode.
add more constants to exitcodes.py
convert to using salt defined exit codes
use salt exit codes
use salt exit codes
use salt defined exit codes
use salt defined exit codes.
use salt exitcodes everywhere.
make sure to import salt.exitcodes
Merge pull request #18860 from terminalmage/issue17963

Fix jinja search path for local file_client
Merge pull request #18894 from cro/fbsd_sockstat

Add support for sockstat on FreeBSD as an alternative to lsof