Make EShell a subclass of UniqueApp and handle single-instance negotiation.

When another Evolution process is running:

  - Running "evolution" will simply present the existing windows.

  - Running "evolution -c <view>" will open a shell window set to <view>.

  - Running "evolution <uri>" will open an appropriate window for <uri>.

The second process will then terminate immediately.


svn path=/branches/kill-bonobo/; revision=37147