stats: break out common QtQuick part of the code

Move most of the QtQuick code to its own directory, so that it
can be reused in the future for the chart.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>

qt-quick/CMakeLists.txt

@@ -0,0 +1,19 @@
+# code for qt-quick based charts
+include_directories(.
+	${CMAKE_CURRENT_BINARY_DIR}
+	${CMAKE_BINARY_DIR}
+)
+
+set(SUBSURFACE_QTQUICK_SRCS
+	chartitem.cpp
+	chartitem.h
+	chartitemhelper.h
+	chartitem_ptr.h
+	chartview.cpp
+	chartview.h
+)
+
+source_group("Subsurface qtquick sourcecode" FILES ${SUBSURFACE_QTQUICK_SRCS})
+
+add_library(subsurface_qtquick STATIC ${SUBSURFACE_QTQUICK_SRCS})
+target_link_libraries(subsurface_qtquick ${QT_LIBRARIES})