Rewrite inventory/ini.py

Now we accept IPv6 addresses _with port numbers_ only in the standard
[xxx]:NN notation (though bare IPv6 addresses may be given, as before,
and non-IPv6 addresses may also be placed in square brackets), and any
other host identifiers (IPv4/hostname/host pattern) as before, with an
optional :NN suffix.

Based on a patch by @Richard2ndQuadrant.

(There's no compelling reason to do this right now, but should be parser
need to be called multiple times in future, this makes it easier.)

The new code parses INI-format inventory files in a single pass using a
well-documented state machine that reports precise errors and eliminates
the duplications and inconsistencies and outright errors in the earlier
three-phase parsing code (e.g. three ways to skip comments). It is also
much easier now to follow what decisions are being taken on the basis of
the parsed data. The comments point out various potential improvements,
particularly in the area of consistent IPv6 handling.

On the ornate marble tombstone of the old code, the following
inscription is one last baffling memento from a bygone age:

-    def _before_comment(self, msg):
-        ''' what's the part of a string before a comment? '''
-        msg = msg.replace("\#","**NOT_A_COMMENT**")
-        msg = msg.split("#")[0]
-        msg = msg.replace("**NOT_A_COMMENT**","#")
-        return msg

Add win_splitdrive filter for windows users

Update faq

Guru is not a thing any more.

Don't convert nulls to strings.

Update dependencies for pywinrm

This change is similar to https://github.com/ansible/ansible/pull/10465

It extends the logic there to also support none types.  Right now if you have
a '!!null' in yaml, and that var gets passed around, it will get converted to
a string.

eg. defaults/main.yml
```
ENABLE_AWESOME_FEATURE: !!null # Yaml Null
OTHER_CONFIG:
  secret1: "so_secret"
  secret2: "even_more_secret"

CONFIG:
  hostname: "some_hostname"
  features:
    awesame_feature: "{{ ENABLE_AWESOME_FEATURE}}"
  secrets: "{{ OTHER_CONFIG }}"
```

If you output `CONFIG` to json or yaml, the feature flag would get represented in the output
as a string instead of as a null, but secrets would get represented as a dictionary.  This is
a mis-match in behaviour where some "types" are retained and others are not.  This change
should fix the issue.

I also updated the template test to test for this and made the changes to v2.

Added a changelog entry specifically for the change from empty string to null as the default.

Made the null representation configurable.

It still defaults to the python NoneType but can be overriden to be an emptystring by updating
the DEFAULT_NULL_REPRESENTATION config.

cloudstack: fixes and consistency change

Make get_group run in O(n*log(n)) instead of O(n^2) by using a cache (#9437 rebase)

changed local_action to alias to connection=local vs delegate_to=locahost

double the speed of loading a 10k host inventory file (#10034 rebase)

first off, we add an oddly slow basic test of 10k item inventory

Before:
```
Ran 229 tests in 13.214s

OK

real    0m13.403s
user    0m12.106s
sys 0m1.155s
```

After:
```
Ran 230 tests in 21.328s

OK

real    0m21.516s
user    0m20.099s
sys 0m1.275s
```

since that seems like a bit long for the test to add to runtime, lets profile

`python -m cProfile -s time ./bin/ansible all -i test/units/inventory_test_data/huge_range --list-hosts`

Before:
```
         1272607 function calls (1259689 primitive calls) in 8.497 seconds

   Ordered by: internal time

   ncalls  tottime  percall  cumtime  percall filename:lineno(function)
    10000    4.393    0.000    4.396    0.000 __init__.py:395(_get_host)
    20000    2.695    0.000    2.697    0.000 __init__.py:341(__append_host_to_results)
    40369    0.113    0.000    0.113    0.000 {posix.lstat}
    50006    0.102    0.000    0.153    0.000 __init__.py:1490(combine_vars)
    40008    0.089    0.000    0.202    0.000 __init__.py:1546(_load_vars_from_path)
    20195    0.088    0.000    0.088    0.000 {posix.stat}
    10011    0.087    0.000    0.087    0.000 {posix.getcwd}
```

The top two lines are promising optimization targets

- populate Inventory's host cache more in _get_host, as we are looping
  over all the groups anyways.

- eliminate duplicate check of whether we've already included a host
  in the construction around __append_host_to_results we can infer
  presence of a host in the results list implies the presence of its
  name in the hostnames set, allowing us to only to the less expensive
  of the two checks

After:
```
         1252610 function calls (1239692 primitive calls) in 1.320 seconds

   Ordered by: internal time

   ncalls  tottime  percall  cumtime  percall filename:lineno(function)
    40369    0.105    0.000    0.105    0.000 {posix.lstat}
    50006    0.094    0.000    0.141    0.000 __init__.py:1490(combine_vars)
    40008    0.081    0.000    0.184    0.000 __init__.py:1546(_load_vars_from_path)
    10011    0.080    0.000    0.080    0.000 {posix.getcwd}
    20195    0.074    0.000    0.074    0.000 {posix.stat}
    10002    0.069    0.000    0.261    0.000 __init__.py:1517(load_vars)
```

fixes #11998, but still leaves issue of delegate_to: localhost not working

Updates to Windows Azure inventory from Tower.  

changed check to avoid OS X broken sem_getvalue()

fixes #11988

fixes #11907

refactored the options a bit, new inventory_opts made sense to always group
fixes #7917

fixes #11979