Add data augmentation procedures

[MCFlowMace]

We want to be able to augment existing noise-free locust simulation data to create larger datasets out of that in a consistent way.

• Addition of noise (different types)
• Shifts in time
• Variation of signal length
• Create pileup signals
• More ideas?

Should go into a new submodule, with structured functions or classes.

[MCFlowMace]

@Wouter-VDP I have assigned you for this since you wanted to work on it. But just let me or @charstnut know if we should jump in.