Time all the preprocessing operations and determine which slow ones can be done beforehand - redefine RMS Rect more efficiently

[tkarab]

Work is initially done in test.py. Will then be moved into preprocessing.py and task_generator.py

• [x] Time all operations (RMS, LPF, SUBSAMP, DISCARD, SEGMENT)
• [x] Move 'apply preprocessing' function to different source file, make it so that it can be called from command prompt using if name == "main"
• [x] Create RMS-Rectified data offline for different window sizes
• [x] Save some results in a folder
• [x] Faster / more efficient RMS Rectification algorithm
• [x] change rms calculation by only subtracting the 2 sub arrays of the cumulative sum array and test if it's faster
• [x] Make RMS script so that it creates folder only upon saving processed data