Makefile: tunable optimization level
Makefile: fix a typo
Makefile: disable gprof by default
Makefile: select c++11
begin detaching sdl specific code
implement ZenTimer
report only failure
prepare configurability of presentation
implement NoPresentation and use it and getopt()
SdlPresentation: encapsulate all SDL-specifics
get rid of global state
detach arena
dependency generation
detach zentimer
detach SdlPresentation