fixes#921
- use view.close instead of nvim-tree.close
- put preview code inside the execution logic on keypress
- sort keys in keypress_funcs
- remove empty buffer when hijacking window
(non breaking, old assignments link to new assignments)
- move lib.collapse-all into actions/collapse-all
- move lib.dir-up into actions/dir-up
- move lib.change-dir into actions/change-dir
- use setup option for change-dir global (and use the old option for
setup)
- move trash.lua into actions
- move system-open from root file to actions
- move copypasta code from fs to actions
- add file_exists in utils
- add rename_loaded_buffers in utils (might need to move that in the
future).