initbpm.m: update names of .m libraries
First version with new DDC simulation
remove redundant functions and update function name from fft2 to fourierseries
Merge branch 'bpm-sim'
acquisition_parameters.m: rename function
ddc_sim.m: change window input of fourierseries function

According to the new behavior of the fourierseries function, the window input shall be a vector instead of function handle.