Fix slow tab switching while folding restoring.

Resolve slow tab switching of folded XML file by setting the isFolding
flag to true, so it can ignore events while folding is taking place, when
switching tabs and when loading the next tab after deleting a tab.
(closes #168, fixes #236 #329)

PowerEditor/src/Notepad_plus.cpp

@@ -3169,7 +3169,9 @@ bool Notepad_plus::removeBufferFromView(BufferID id, int whichOne)
 				toActivate = active;    //activate the 'active' index. Since we remove the tab first, the indices shift (on the right side)
 			}
 			tabToClose->deletItemAt((size_t)index); //delete first
+			_isFolding = true; // So we can ignore events while folding is taking place
 			activateBuffer(tabToClose->getBufferByIndex(toActivate), whichOne);     //then activate. The prevent jumpy tab behaviour
+			_isFolding = false;
 		}
 	}
 	else

PowerEditor/src/NppNotification.cpp

@@ -263,8 +263,11 @@ BOOL Notepad_plus::notify(SCNotification *notification)
 			switchEditViewTo(iView);
 			BufferID bufid = _pDocTab->getBufferByIndex(_pDocTab->getCurrentTabIndex());
 			if (bufid != BUFFER_INVALID)
+			{
+				_isFolding = true; // So we can ignore events while folding is taking place
 				activateBuffer(bufid, iView);
-
+				_isFolding = false;
+			}
 			break;
 		}