PHP already tracks all included files, through the mechanisms employed by the *_once include/require methods. The collection of all included files can be retrieved through get_included_files().
Removed the local property _ci_loaded_files and the implementations where newly included files are added to the collection.
Replaced the enquiring of included files with the built in PHP functionality.
Unit tests to reproduce the problem raised in #353.
In addition to testing load by libary or load by driver we are also extending by prefixed sub-class.
Added new mack application folder.
Added Session Subclass mock.
Fix bootstrap to point APPPATH to the mock application folder.
Including IC_Session class more than once in the same unit test requires runInSeparateProcess and preserveGlobalState disabled
which also causes all knowledge of bootstrap to dissapear so we need to cater for that.
To extend the Session and drivers you would add same named drivers to the valid_drivers collection.
This allows you to still fall back to the standard session drivers eves thaugh we extended CI_Session.
Also helps solving problems discovered in #353.