support for exprlib syntax for formulate

gistfile1.php

static public function build($formula, $isCalculable = self::CALCULABLE)
{
    return new Formula($formula, $isCalculable);
}

public function setVars(array $vars)
{
    $this->parameterBag->datas = array_merge($this->parameterBag->datas, $vars);

    return $this;
}

public function evaluate()
{
    return $this->render();
}