[Dolphin] Linked folders: extend places panel

This idea is similar to link file to activity, but do not requires activities.

It is about to allow extend places panel more dynamically in this way:

  1. Allow to set current location related places. These could be stored in .desktop file, or in separate place as group of directories, so there is no config-related problems.
  2. Allow to add places by other app. It could work via command line or path to special config file (both on launch) or dbus

Usage:

  1. I ran copy-dolphin-into /home/a/movies and destination item appear
  2. I add build directory, sources and documentation directories to places of my project. When I am in subdirectory of project directory, these items appear.