title: std::regex, to match begin/end of string
body: <p>In JS regular expressions symbols <code>^</code> and <code>$</code> designate <strong>start and end of the string</strong>. And only with <code>/m</code> modifier (multiline mode) they match <strong>start and end of line</strong> - position before and after CR/LF.</p>
  
  <p>But in <a href="http://www.cplusplus.com/reference/regex/ECMAScript/">std::regex</a>/ECMAscript mode symbols <code>^</code> and <code>$</code> match <strong>start and end of line</strong> always.</p>
  
  <p>Is there any way in std::regex to define <strong>start and end of the string</strong> match points? In other words: to support JavaScript multiline mode ...</p>