Revert "EditorManager: Fix crash when closing an editor upon activation"

Deleting an editor while currentEditorChanged is apparently not a good
idea.
Use a queued connection instead.

This reverts commits 243a625961,
447c4ed37f,
d9602ca550 and
3103487038.

Change-Id: Iccbee25fb77714963faa6f7184d1f5f53ed348a6
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@digia.com>
Reviewed-by: Eike Ziller <eike.ziller@digia.com>

src/plugins/coreplugin/coreplugin.pro

@@ -237,6 +237,6 @@ else:unix {
 OTHER_FILES += editormanager/BinFiles.mimetypes.xml
 
 equals(TEST, 1) {
-    SOURCES += plugintestutils.cpp
-    HEADERS += plugintestutils.h
+    SOURCES += testdatadir.cpp
+    HEADERS += testdatadir.h
 }