Added remote_autostart_ignore config setting

This patch adds the "xdebug.xdebug.remote_autostart_ignore" setting xdebug. It's a comma-separated list of (partial) URI's which should NOT trigger the remote_autostart. The list is automatically sanitized, but every URI must start with a / in order to match the actual uri (it matches the $_SERVER['REQUEST_URI'] variable).

Example:

    xdebug.remote_autostart = 1
    xdebug.remote_autostart_ignore = "/phpmyadmin,/wordpress,/admin"

will trigger xdebug on every request, except for URL's like:
    /phpmyadmin/index.php
    /wordpress/wp-admin/index.php
    /admin/dashboard 
    etc..


It looks functional (at least, on my system). I'm not 100% sure about the TSRM vars though.