dont lock Ports table if mac is empty

this is a performance optimization
commitAddPort: check mac before lock
commitUpdatePort: idem
alreadyUsedL2Address: optimize SQL query to use index (BINARY cast
		prevents using index)
dont display routers in aggregate networks (#773)

	renderIPSpaceRecords: use own_addrlist instead of addrlist
	printRoutersTD: inject hl_ip param into router href
bugfix in config edit form (user-defined vars)

loadConfigDefaults: return array, dont modify global
alterConfigWithUserPreferences: removed unused global $userConfigCache
renderUIConfig: use loadConfigDefaults, not the $configCache global
renderConfigEditor: idem
trim trailing whitespace