Resources (#1)

* start some resource fiddling

* start some resource fiddling

* initiate a real resource manager

* fix color flicker in rendering

* delete unintended constructors

and add a convenience function to reset the render-image (from the
original image, aka. clone again)

* [OpenGL deprecation warning]

The compiler said that these functions are "deprecated". They seem to
be useless anyway...

* various improvements

* add resource enumerator and documentation

* fix constness stuff

* use existing iterator for insertion

* init unit tests

* rm bogus file

---------

Co-authored-by: m-aXimilian <keuffnermax@gmail.com>

lib/imaging/CMakeLists.txt

@@ -6,7 +6,7 @@ message(STATUS "Found opencv: " ${OpenCV_INCLUDE_DIRS})
 message(STATUS "OpenCV_LIBs from: " ${OpenCV_LIBS})
 
 set(IMAGELIBSRC
-  Image.cpp)
+  PixelariumImage.cpp)
 
 set(IMAGELIBLIBNAME pixelariumimagelib)
 
@@ -20,4 +20,4 @@ target_link_libraries(${IMAGELIBLIBNAME}
 
 target_include_directories(${IMAGELIBLIBNAME}
   PUBLIC ${OpenCV_INCLUDE_DIRS}
-  PRIVATE ${LIBCZI_INCLUDE_DIR})
+  PRIVATE ${LIBCZI_INCLUDE_DIR})