Add Dynamical Decoupling experiment files

[mooligan3]

Five new files:

• Decoherence Visualisation (experiment sketch 1)
• Simplified Dynamical Decoupling (experiment sketch 2)
• Realistic Dynamical Decoupling (experiment sketch 3)
• Lesson1.h (header file that carries all required functions for the experiments)
• Fixed Horizontal Axis (test to demonstrate a horizontal axis that is updated inertially)

Edited:

• Qbead.h header file - added the variable 'd' to the Qbead class to track internal timestep for horizontal axis update

TO DO:

• All of the files still need to be commented!!! Most comments are missing and the comments that exist are unformatted/unclear/incorrect - I will fix this
• The three experiment sketches periodically show a flash of white LEDs - I don't fully understand why this happens but I'll keep looking to fix it
• The horizontal axis in the 'Fixed Horizontal Axis' has been slightly bugged for me in the past few weeks - I will determine the cause and fix. The 2D dynamical decoupling experiment will be added once this is fixed