[TYPO3-core] RFC Bug #7386: Remove hardcoded references to alt_main.php backend interface

[Jeff Segars]

Hey guys,

This is a SVN patch request.

Type: Bugfix

Bugtracker references: http://bugs.typo3.org/view.php?id=7386

Branches: Trunk

Problem:
Various places in the core are hardcoded to use the alt_main.php backend 
interface. These include the workspace selector within the User 
tools->Workspace, the Admin Panel link to the backend, and several other 
locations.

Solution:
Add a function to t3lib_BEfunc to get the current backend script and use 
this function instead of the hardcoded alt_main.php

Thanks,
Jeff