* Monodoc/provider.cs: Overview: MonoDevelop loads monodoc.dll into

	* Monodoc/provider.cs: Overview: MonoDevelop loads monodoc.dll into
	  it's own process, and spawns monodoc GUI into a separate process,
	  then sends Node.URL values (obtained from the MonoDevelop process)
	  to load the documentation into the monodoc GUI.  Problem:
	  occasionally the requested documentation isn't loaded, but instead
	  some completely unrelated documentation is shown instead.  This is
	  because the Node.URL value contains HelpSource-dependent data, e.g.
	  a Node.URL value of "ecma:0#Foo/" will specify the 1st file
	  within...whatever HelpSource is first consulted by monodoc (which
	  can vary between monodoc runs, the phase of the moon, etc.).
	  Solution: Add a Node.PublicUrl property which returns _stable_ URLs
	  which aren't specific to a given HelpSource.
	  - Add Node.PublicUrl property, which delegates to
	    Provider.GetPublicUrl(string), so that a Provider can generate a
	    Provider-independent URL (if possible).
	  - Print PublicUrl from Node.PrintTree().
	  - Add RootTree.GetSupportedFormats(), RootTree.GetProvider()
	    methods.
	  - Make RootTree.GetHelpSource() public.
	* Monodoc/ecma-provider.cs: Add EcmaDoc.GetCref() method (generates an
	  XML documentation //see/@cref value), override
	  Provider.GetPublicUrl() (which will return cref's if possible).

svn path=/trunk/mcs/; revision=131923