(legacy)  add support to system_usermanager.php for edit/add new using GET in addition to POST, needed for other modules to link to this page in a more natural way.

Page need proper cleaning.

(legacy) fix dependencies, related to crashreport "PHP Fatal error:  Call to undefined function services_dnsmasq_configure() in /usr/local/etc/inc/interfaces.inc on line 3098"

(legacy) fix crash report "PHP Warning:  explode() expects parameter 2 to be string, array given in /usr/local/www/interfaces_bridge_edit.php on line 290"

(legacy) fix crashreport " PHP Warning:  Illegal string offset 'vip' in /usr/local/www/carp_status.php on line 124"

(legacy) fix crashreport " PHP Warning:  Illegal string offset 'ifgroupentry' in /usr/local/www/firewall_rules_edit.php on line 869"

(legacy) fix crashreport  PHP Warning:  substr_count(): Empty substring in /usr/local/www/services_ntpd.php on line 290

(legacy) fix crashreport  PHP Warning:  htmlspecialchars() expects parameter 1 to be string, array given in /usr/local/www/services_dhcp_relay.php on line 185

(legacy) fix crashreport " PHP Warning:  Illegal string offset 'item' in /usr/local/www/services_dnsmasq_edit.php on line 250"

(legacy) fix crashreport "PHP Warning:  Illegal string offset 'if' in /usr/local/etc/inc/filter.inc on line 394"

(legacy) fix some crash reports, related to " PHP Fatal error:  Call to undefined function lookup_gateway_ip_by_name() in /usr/local/etc/inc/system.inc on line 151"

fix interfaces.inc dependency for lookup_gateway_ip_by_name in system_resolvconf_generate