[TYPO3-core] RFC #11293: Login page is not translatable

[Benjamin Mack]

Hey,

this is a SVN patch request.

Type: feature

BT reference: http://bugs.typo3.org/view.php?id=11293

Problem:
the login page is not translatable. The labels are hardcoded and taken 
from the TYPO3_CONF_VARS['BE']['loginLabels']. However, through 
modifications in init.php, the $LANG object is now available on the 
login screen as well.

Solution:
Get rid of the | label-style for the login page, do an auto-detection of 
the preferred language and load all labels from the $LANG object.

The attached patch does the following:
* Browser detection of the language (HTTP_ACCEPT_LANGUAGE) and sets it, 
if no user is logged in.
* Extracts all labels into a new locallang_login.xml file. There are 
some additional labels not in use right now because there are some 
modifications that will come in a separate patch.
* Has a backwards-compatible option to check if the 
$TYPO3_CONF_VARS['BE']['loginLabels'] was changed for the installation. 
If so, it overrides the LLvalues from the config option.
* Some labels were moved to a later stage of substituteMarkerArray so 
they can be used in other parts of the template as well (not just in the 
form subpart).
* Some minor code cleanup.

All the best,
Benni.