ref - extract FileList and FileListModel interfaces
imp - transfer focus to file list on app start
ref - split FileBrowser initialization into methods
fix - change show hidden files button and menu item states consistently

refact file browser components structure completely
ref - replace FileBrowserToolbar class with individual button classes
add - "File > Quit" menu Item
ref - multiple changes, see below

extract FileListEntry interface
move methods concerning parent folder to FileList interface from FileListModel
extract ListCellRenderer into a standalone class
delete toggleShowHiddenFiles() method from FileListModel
fix - fix lambda converter in LocalFileListEntry
ref - make FileListModel interface extend javax.swing.ListModel
ref - refact FileList interface into an abstract class
del - delete redundant methods from FileListEntry interface but keep them in the LocalFileListEntry implementation
add - 'throws IOException' clause to FileListEntry.getInputStream()
ref - throw exceptions in FileListModel interface, move showing message popups to Dialogs class
ref - refact FileListModel into abstract parent class

also throw some exceptions
imp - make FileListModel.repaint(0 protected but final
add - hardly working ftp client
ref - pass FileListEntry object into FilePreview instead of name and InputStream