pothos-gui: fix filter on file open dialog
pothos-gui: select editor on open dialog
pothos-gui: all panels are now docks
pothos-gui: save settings on destruction -- definite exit
pothos-gui: remove RemoteNode from remote table and block cache
pothos-gui: save metadata about nodes
pothos-gui: remote nodes settings key rename
pothos-gui: client test connect default server
pothos-gui: no duplicate connections - fix #24
pothos-gui: new block gets top z-index