audio: clamp overflowing values
Merge branch 'master' into audio
jobmanager: add jobmanager and integrate it into engine
jobmanager: fix header guard typo
jobmanager: add this-> to members and add comments
audio: rename ResourceLoader to InMemoryLoader
audio: basic dynamic audio loading is working
audio: add comments, small fixes
Merge branch 'audio' into jobmanager

This brings background loading for audio files.

Conflicts:
	src/CMakeLists.txt
	src/audio/audio_manager.cpp
	src/audio/audio_manager.h
	src/audio/resource_loader.cpp
	src/audio/resource_loader.h
	src/engine/audio/in_memory_loader.cpp
	src/engine/audio/resource_loader.cpp
	src/engine/engine.cpp
	src/engine/engine.h
	src/engine/init.cpp
testing: using dynamic background audio loading
util/fps: properly initialize variables for fps counter
engine: removed unique_ptr for the global engine instance

this fixes the segfault in ftgl/freetype.
testing: fixed memleaks in generated filenames

the free could be skipped when the loop is continued.