[TYPO3-core] Improved page tree (and lots of other fixes)

[Martin Kutschker]

Dmitry Dulepov [typo3] schrieb:
> So by  default it will be disabled for old and enabled for new installations.

Sadly such a scheme doesn't work, because of the sub-optimal way defaults 
are set. You don't know if the installation is new, or the config variable 
simple was never set.

A solution for $TYPO3_CONF_VARS could be to create a typo3conf/config.txt 
from config_defaults.php as serialized array. config.txt should only be 
created once during the installation. It will contain the original 
defaults. localconf.php will be run after loading the data from config.txt.

I think that we can with this mechanism decide if we want to set some new 
defaults or not without having to fear we breal old sites.

Masi