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/utilities/ILog.hpp

@@ -3,6 +3,14 @@
 
 namespace pixelarium::utils::log
 {
+enum class LogLevel
+{
+    Trace = 1 << 0,
+    Debug = 1 << 1,
+    Info = 1 << 2,
+    Warn = 1 << 3,
+    Error = 1 << 4,
+};
 class ILog
 {
    public:
@@ -10,8 +18,9 @@ class ILog
     virtual void Debug(const std::string& msg) = 0;
     virtual void Warn(const std::string& msg) = 0;
     virtual void Error(const std::string& msg) = 0;
+    virtual void ChangeLevel(LogLevel lvl) = 0;
 
     virtual ~ILog() {}
 };
 
-}  // namespace pixelarium::utils::log
+}  // namespace pixelarium::utils::log