Allow missing projects to be removed from solution.

Remove menu item is now enabled for a missing project.

src/Main/Base/Project/ICSharpCode.SharpDevelop.addin

@@ -552,12 +552,14 @@
 			          icon  = "Icons.16x16.PasteIcon"
 			          loadclasslazy = "false"
 			          class = "ICSharpCode.SharpDevelop.Project.Commands.PasteProjectBrowserNode"/>
-			<MenuItem id = "Remove"
-			          label = "${res:Global.RemoveButtonText}"
-			          type = "Item"
-			          icon  = "Icons.16x16.DeleteIcon"
-			          loadclasslazy = "false"
-			          class = "ICSharpCode.SharpDevelop.Project.Commands.DeleteProjectBrowserNode"/>
+		</Condition>
+		<MenuItem id = "Remove"
+		          label = "${res:Global.RemoveButtonText}"
+		          type = "Item"
+		          icon  = "Icons.16x16.DeleteIcon"
+		          loadclasslazy = "false"
+		          class = "ICSharpCode.SharpDevelop.Project.Commands.DeleteProjectBrowserNode"/>
+		<Condition name="WriteableProject" action="Disable">
 			<MenuItem id = "Rename"
 			          label    = "${res:ProjectComponent.ContextMenu.Rename}"
 			          shortcut = "F2"