getTempParentFolder() in framewor/core/TempPath.php checks for silverstripe-cache directory in webroot first, failing that it falls back on the sys_get_temp_dir() folder.
also, getTempFolder() is no longer in framework/core/Core.php since #b075fa29c59f970bea31bbe8be1bd6560a8778b6, it is now located in framework/core/TempPath.php
Makes setups which are completely driven by that file a bit easier
to automate, particularly if the same codebase is deployed
multiple times (e.g. to a staging and live instance)
The _ss_environment.php file can now be in any parent folder of the framework (according to realpath())
Removing the description of '3 levels deep' and replaced with explanation of infinite depth.
