Contain retained assets and paint document paths

cmake/PanoPainterSources.cmake

@@ -1,22 +1,28 @@
 set(PP_LEGACY_ENGINE_SOURCES
+    src/hmd.cpp
+    src/log.cpp
+    src/mp4enc.cpp
+    src/util.cpp
+    src/wacom.cpp
+)
+
+set(PP_LEGACY_ASSETS_IO_SOURCES
     src/abr.cpp
-    src/action.cpp
     src/asset.cpp
-    src/bezier.cpp
     src/binary_stream.cpp
+    src/image.cpp
+    src/serializer.cpp
+    src/settings.cpp
+)
+
+set(PP_LEGACY_PAINT_DOCUMENT_SOURCES
+    src/action.cpp
+    src/bezier.cpp
     src/brush.cpp
     src/canvas.cpp
     src/canvas_actions.cpp
     src/canvas_layer.cpp
     src/event.cpp
-    src/hmd.cpp
-    src/image.cpp
-    src/log.cpp
-    src/mp4enc.cpp
-    src/serializer.cpp
-    src/settings.cpp
-    src/util.cpp
-    src/wacom.cpp
 )
 
 set(PP_LEGACY_RENDERER_GL_SOURCES