Added contributed linux build by Martin Schreiber.
core.h now includes cstddef. Also, math.h was changed to cmath
Makefile order of final compilation changed, to put includes and libraries on the end
Beta version of a time version using chrono, from C++11. Makefile was adjusted accordingly. This created a bug on *ballistics demo, but other demos seems ok
Corrected bug on *ballistic demos. I needed to update startTime to double
Added missing features on timing.cpp. It now calculates FPS, averageFrameDuration. Clock ticks calculation is still missing