New addons configuration screen, to select/unselect which addons will load;...

New addons configuration screen, to select/unselect which addons will load; can be used to enable addons with version mismatches too, at your own risk

git-svn-id: http://svn.net-core.org/repos/t-engine4@4909 51575b47-30f0-44d4-a5cc-537603b46e54