Feature request: Jump to placeholder locations for behat snippets

[FMCorz]

The auto complete list of available behat steps when writing tests is amazingly useful. It would be awesome if after completing one, the placeholder elements had tab triggers so that they can typed in right away.

With snippets, this can be done by declaring the $x parameters, I wonder if this can used here.

	"get_string": {
		"scope": "php",
		"prefix": [
			"getstr",
			"get_string"
		],
		"body": [
			"get_string('${1}', '${2:block_gearup}')$0"
		],
		"description": "Shortcut to get_string()."
	},