Fixing PHP warnings.
Minor - format code.
The session ends the end_date at 23.59.59 see BT#7740
Minor - fixing PHP warning.
Adding 23:59:59 as  end_date limit see BT#7740
Fixing wrong label.
Fixing label bis.
Showing toolbar in messages see BT#7739
Minor - format code.
Minor - Fixing comments, fixing PHP warnings.
Moving old wiki code into a Wiki class, removing global calls.
Replacing Database::get_user_info_from_id() (deprecated function) with api_get_user_id().
Formatting queries.
Fixing queries.
More cleaning, lots of PHP warnings fixed, fixing UI.
Fixing query and format code.
Merge branch '1.9.x' of github.com:chamilo/chamilo-lms into 1.9.x
wiki css update