A thunar dropbox plugin that allows to copy links and
add files to dropbox.
Depends on new `xfce.thunarx-2-dev` plugin sdk package instead of
thunar. Doing so seem standard on other distributions such as
Ubuntu and narrows depedencies to only the sdk headers (i.e.:
what's needed by plugins).
Note that replacing the `xfce.thunarx-2-dev` dependency directly
by `xfce.thunar` work equally well. However it now would be
impossible for the `thunar` executable to depend on the plugin.
Tests:
- When dropbox daemon active, functionalities are added
to right click on file and folders menu.
- When dropbox daemon inactive, functionalities **not** added
to menu.
- Successfully copied a dropbox link.
- Successfully moved a file to dropbox.
