implement 'wp post generate --post_content=<content>'
Introduce a helper method for launching a new WP-CLI process using the same context as the current process.
Now that we have a method to launch new WP-CLI processes, use it to flush rewrite rules after setting the structure.

Fixes #814
These arguments should be optional
Call the PHP binary directly, and ensure all arguments are escaped
Implements 'wp plugin deactivate --all' function
Implements the 'wp plugin deactivate --all' function
s/action/hook
Deactivate only active plugins.
Merge pull request #886 from tiagohillebrandt/master

Implements the 'wp plugin deactivate --all' function
Make validate_role() return a bool. Throw error at caller if required
Add tests
Fix spacing
Merge pull request #896 from leewillis77/user-role-fix

Dont' ignore --role when creating users Edit
bump version to 0.13-beta
add test case for activating network-only plugins
check if plugin is network-only
Merge pull request #850 from wp-cli/fix-850

Misleading confirmation message when activating network-only plugins
clarify inline docs for --format parameter; fixes #884
Merge pull request #845 from wp-cli/hooks

WP_CLI::add_action() and WP_CLI::do_action() are confusing