Qt Creator CMake port

Based on Tobias Hunger's work from a few months ago.

The CMake configuration needs libclang and Qt paths specified as
CMAKE_PREFIX_PATH.

Auto tests are run with "ctest". At the moment the pass rate is 87%.

Change-Id: Iba98e39bf22077d52706dce6c85986be67a6eab0
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/diffeditor/CMakeLists.txt

@@ -0,0 +1,22 @@
+add_qtc_plugin(DiffEditor
+  PLUGIN_DEPENDS Core TextEditor
+  DEFINES DIFFEDITOR_LIBRARY
+  SOURCES
+    descriptionwidgetwatcher.cpp descriptionwidgetwatcher.h
+    diffeditor.cpp diffeditor.h
+    diffeditor.qrc
+    diffeditor_global.h
+    diffeditorconstants.h
+    diffeditorcontroller.cpp diffeditorcontroller.h
+    diffeditordocument.cpp diffeditordocument.h
+    diffeditorfactory.cpp diffeditorfactory.h
+    diffeditoricons.h
+    diffeditorplugin.cpp diffeditorplugin.h
+    diffeditorwidgetcontroller.cpp diffeditorwidgetcontroller.h
+    diffutils.cpp diffutils.h
+    diffview.cpp diffview.h
+    selectabletexteditorwidget.cpp selectabletexteditorwidget.h
+    sidebysidediffeditorwidget.cpp sidebysidediffeditorwidget.h
+    unifieddiffeditorwidget.cpp unifieddiffeditorwidget.h
+  EXPLICIT_MOC diffeditor.h
+)