Add option for deleting history entries and refactor dialogs

- Refactor FileDialog and HightlightDialog into ButtonDialog
- Create a new ButtonDialog when a file in the History dialog is hold,
  offering an option to delete the history entry.
If selected file is a directory, paste inside it
Refresh current path in filemanager after file operation

This behavior is more consistent when e.g. a file is moved to ".."
Merge pull request #489 from thotypous/master

File manager improvements