Exact location of CI files

@John_Betong ... I used to setup my apps the way you do, but now have way too many apps, and prefer to update them (regarding CI version) 1 at a time, rather than all at once, in case something breaks. I have over 80 apps, using all versions of CI ... some of those are legacy and will not be updated.

A composer version of the framework might make it easier, or configuring it as a git submodule, although those strategies would still end up with a copy of CI inside each app.

The setup detailed in my previous #post:
1.  only requires a single copy of the CI-Version 
2.  each index.php  uses $sytem_path to call any CI-Version
3.  each index.php  uses $application to call any Application-version
4. I think $appication can be set to call  the CI-version/application

I fail to see how Composer simplifies the version selection.