Setting custom BP_SETTINGS_SLUG breaks notifications/delete settings links

[fiskhandlarn]

in bp_core_add_settings_nav(), the subnav urls are set by hardcoded "settings/" urls, rather than using the BP_SETTINGS_SLUG constant.

If one were to define BP_SETTINGS_SLUG to something else than "settings" (e.g. in bp-custom.php), bp won't find /members/xxx/settings/notifications/ for example anymore, and therefore redirect the user to the site root when clicking on notifications in the submenu.

A fix for this could be substituting this line:

$settings_link = $bp->loggedin_user->domain . 'settings/';

with either one of these:

$settings_link = $bp->loggedin_user->domain . BP_SETTINGS_SLUG . '/';

$settings_link = $bp->loggedin_user->domain . $bp->settings->slug . '/';

[johnjamesjacoby]

(In [2123]) Fixes #1249