v0.2.0

With v0.2.0 gearshifft provides better latency and more accurate timings as well as more command-line arguments for fftw. Further improvements:

• error-bound (=1e-5), number of warmups (=1) and number of runs (=10) can be set via cmake
• the data for FFT is no more using randoms but a see-saw function
• the csv outputs have been improved