Fix possible file corruption during macro playback

closes #1007, closes #919, closes #834
When backups are enabled, playing back a macro that takes a while can
corrupt a file (see the mentioned issues). I tested this with a ~100,000
line text file, ~3.3MB in size. Created a macro of Down5, Delete10. Played
this till the end of the file. Took about 20s to run so it had a few
backup cycles during it. Reproduced it fairly easily and never had it
happen after this adjustment.

PowerEditor/src/NppCommands.cpp

@@ -42,6 +42,8 @@ using namespace std;
 
 void Notepad_plus::macroPlayback(Macro macro)
 {
+	LongRunningOperation op;
+
 	_pEditView->execute(SCI_BEGINUNDOACTION);
 
 	for (Macro::iterator step = macro.begin(); step != macro.end(); ++step)