Merge remote-tracking branch 'ztree/master'

1) Removed redundant comments about compatibility with GNU Emacs
2) Removed workaround for electric-indent-mode

diff --cc packages/ztree/ztree-diff-model.el
Simple merge

diff --cc packages/ztree/ztree-diff.el
Simple merge

diff --cc packages/ztree/ztree-dir.el
Simple merge

diff --cc packages/ztree/ztree-util.el
Simple merge

diff --cc packages/ztree/ztree-view.el
Simple merge

diff --cc packages/ztree/ztree.el
Simple merge