* add todo
* refactor(#2886): multi instance: node class refactoring: extract links, *_git_status (#2944)
* extract DirectoryLinkNode and FileLinkNode, move Node methods to children
* temporarily move DirectoryNode methods into BaseNode for easier reviewing
* move mostly unchanged DirectoryNode methods back to BaseNode
* tidy
* git.git_status_file takes an array
* update git status of links
* luacheck hack
* safer git_status_dir
* refactor(#2886): multi instance: node class refactoring: DirectoryNode:expand_or_collapse (#2957)
move expand_or_collapse to DirectoryNode
* refactor(#2886): multi instance: node group functions refactoring (#2959)
* move last_group_node to DirectoryNode
* move add BaseNode:as and more doc
* revert parameter name changes
* revert parameter name changes
* add Class
* move group methods into DN
* tidy group methods
* tidy group methods
* tidy group methods
* tidy group methods
* parent is DirectoryNode
* tidy expand all
* BaseNode -> Node
* move watcher to DirectoryNode
* last_group_node is DirectoryNode only
* simplify create-file
* simplify parent
* simplify collapse-all
* simplify live-filter
* style
* move lib.get_cursor_position to Explorer
* move lib.get_node_at_cursor to Explorer
* move lib.get_nodes to Explorer
* move place_cursor_on_node to Explorer
* resolve resource leak in purge_all_state
* move many autocommands into Explorer
* post merge tidy
