Fix #364 - Admin > users > edit: SEF issue when enabled

Admin > users > edit: SEF issue when enabled

the problem was on the **e_ADMIN_AREA** constant in the class2.php file; it was not set properly due to a missing check step in the  **set_urls()** function of the **e107_class.php** file. 

Since usersettings.php file is not a plugin nor an admin file, ( it is on the root directory )  any try to check if we are **inAdminDir** ( we are in fact ADMIN and we are editing ) without a **QUERY_STRING** ( when we are in SEF mode the uri does not provide any query, so, no chance to use ```if(is_numeric(e_QUERY)){ }``` here ) will fail, resulting in **missing lan_file and missing admin_theme** inclusion.

The other problem is the top admin navigation that in SEF mode result in all links pointing on wrong path like **e107/user/edit/e107_admin/...** so i changed all the **e_ADMIN** to **e_ADMIN_ABS** in the **sitelinks_class.php**.

Another problem is that usersettings.php seams to be not fully integrated into the new routing system, so i have removed the old **usersettings_adminmenu()** and replaced with the new **e_admin_dispatcher** and **e_admin_ui** class nothing special just the essential to make it works without problems.

Fix #364


### NOTE ###
be carefull in using code like this: ```if(e_ADMIN_AREA) { echo e_ADMIN_AREA; //output e_ADMIN_AREA  }``` if the constant is not defined and error_reporting is set to 0 it evaluate like true. instead use something like ```if(defined(e_ADMIN_AREA)){ }``` or at least ```if( e_ADMIN_AREA === true ) {  }```