Merge pull request #38 from chamilo/1.9.x

1.9.x
Merge pull request #40 from chamilo/1.9.x

1.9.x
Merge pull request #41 from chamilo/1.9.x

1.9.x
Merge pull request #42 from chamilo/1.9.x

1.9.x
Merge pull request #43 from chamilo/1.9.x

1.9.x
Merge branch '1.9.x' of github.com:chamilo/chamilo-lms into 1.9.x
Merge pull request #44 from chamilo/1.9.x

1.9.x
messages/outbox: Fix undefined var warnings

This code needs urgent refactoring. I just applied something similar to
what other files in this module are doing.
lib/messages.lib: Undefined variable warning
Minor - adding api_get_cidreq()
#6948 add message in multiple lp audio upload form when no items in lp
Minor - format code.
Using GroupManager::user_has_access() to check user group permissions.

See BT#7870
Merge branch '1.9.x' of github.com:chamilo/chamilo-lms into 1.9.x
Minor - adding api_get_cidreq().
Fixing double resursive in delete_document function see BT#7870
Minor - adding add_progress_bar() function see BT#7893
Adding progressbar & adding api_get_cidreq() see BT#7893
Minor - fixing PHP warning.
Adding group filter when deleting a doc see BT#7870