media: add small C++ helper describing a picture struct

By using a std::string instead of a C-string, memory management
becomes so much simpler! This class will be used for keeping track
of deleted/added pictures in the undo system.

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

core/CMakeLists.txt

@@ -127,6 +127,8 @@ set(SUBSURFACE_CORE_LIB_SRCS
 	parse.h
 	picture.c
 	picture.h
+	pictureobj.cpp
+	pictureobj.h
 	planner.c
 	planner.h
 	plannernotes.c