Squashed 'libsrcs/libRocket/libRocket/' changes from eee0de5..59c9858

59c9858 Bugfix: reset data_source to NULL upon detaching

git-subtree-dir: libsrcs/libRocket/libRocket
git-subtree-split: 59c9858423767f737fa7c6752d864fe349cf6504
Merge commit 'a99430fd3e824f4da45bc816acac599f03b21300'