add folding for Imports in VB

ILSpy/VB/VBTextOutputFormatter.cs

@@ -34,6 +34,8 @@ namespace ICSharpCode.ILSpy.VB
 		readonly ITextOutput output;
 		readonly Stack<AstNode> nodeStack = new Stack<AstNode>();
 
+		bool firstImport, lastImport;
+		
 		public VBTextOutputFormatter(ITextOutput output)
 		{
 			if (output == null)
@@ -64,7 +66,15 @@ namespace ICSharpCode.ILSpy.VB
 			//					}
 			//				}
 			//			}
-			
+			if (nodeStack.Count == 0) {
+				if (node is ImportsStatement) {
+					firstImport = !(node.PrevSibling is ImportsStatement);
+					lastImport = !(node.NextSibling is ImportsStatement);
+				} else {
+					firstImport = false;
+					lastImport = false;
+				}
+			}
 			nodeStack.Push(node);
 		}
 		
@@ -100,6 +110,11 @@ namespace ICSharpCode.ILSpy.VB
 				return;
 			}
 
+			if (firstImport) {
+				output.MarkFoldStart(defaultCollapsed: true);
+				firstImport = false;
+			}
+
 			output.Write(identifier);
 		}
 
@@ -198,6 +213,10 @@ namespace ICSharpCode.ILSpy.VB
 		
 		public void NewLine()
 		{
+			if (lastImport) {
+				output.MarkFoldEnd();
+				lastImport = false;
+			}
 			output.WriteLine();
 		}