(less) 2> /dev/null would fail if stdin is /dev/null.
Sinceless --version do not read anything from stdin,
it is perfect for seeing if the software exist or not.

Also replace the whole os system detection by directly
using subprocess ( as we use it elsewhere, we already
depend on it ).

This can be used from another non interactive software, see #9695
for details.

Conflicts:
	lib/ansible/modules/core
	lib/ansible/modules/extras

Add -t OR --tags options to pass to ansible-playbook

more intelligent about ignoring files that are clearly not modules

function

added display of deprecated to ansible-doc
now it does better job of using tty columns
fixed indication truncation of desc with trailing ...
removed extension from module list, also fixed matching exlusion
blacklist

'_', they will be loaded after non prefixed modules are checked they can
be full modules or symlinks to existing ones (alias)

also updated ansible doc to ignore these, will eventually add selective
display

When running `ansible-doc --list` a lot of errors are
generated when `ansible-doc` tries to find documentation
strings in `.pyc` files.

Fixes #9236

using this (for testing purpose) :
  $ ansible-galaxy install COPYING
  - error: the file downloaded was not a tar.gz
  - COPYING was NOT installed successfully.
  - you can use --ignore-errors to skip failed roles.

this result in COPYING being erased, which is surprising for the user.
This also prevent erasing requirements.yml if someone use the wrong flag.

This change fixes hg galaxy roles
Roles also get installed if roles path is missing, which
the tests currently require (fixes #8950)

fixes #8823
	modified:   bin/ansible-galaxy

This option, when set to True, allows "ansible" command to load callback plugins

Fixes #8890

Fixes #8884

Defaults to the system wide `roles-path` when `path` is not specified in the
provided `role-file`.  An example installing nginx to a relative path specified
by the `role-file`.

    - src: https://github.com/bennojoy/nginx
      path: vagrant/roles/

Fixes #8324
Improves #7667

  Only print a blank line between plays when also doing --list-hosts and/or
  --list-tasks, otherwise this output just a long list of blank lines, one for
  each play.

`ansible-galaxy init --offline ...` can create a role without
talking to the galaxy api server
`ansible-galaxy install ...` only needs to talk to the galaxy api
server for galaxy roles, not tar files or scm archives
Fixed a bug in command line role installation