hook_civicrm_navigationMenu prone to conflicted IDs

HR-201 uses hook_civicrm_navigationMenu to register new menu items. In discussion of the pull-request ( https://github.com/civicrm/civihr/pull/190 ), the point was raised that the example code ( http://wiki.civicrm.org/confluence/display/CRMDOC/hook_civicrm_navigationMenu ) would produce problems if use dby multiple extensions. The discussion thread goes into more depth and includes one possible solution ( https://gist.github.com/totten/f56ec772bdf1510572c0 ), but there was some debate about the proper solution.