implemented perform_y

[gsilviHQS]

This is the first step in solving #7 implementing Ry gates (and possibly Rx,Rz) Also added 2 new colors to handle the complex phase.

[gsilviHQS]

I made the following changes:

• factorized the single gates to reduce the code replication.
• add a continuous color wheel for amplitudes
• add Rx,Ry,Rz gate with half_turns
• the command from terminal can accept floats
• add a simplify to the amplitudes to avoid labels too complex ( this part add some overhead but I didn't find a better way to deal with it atm), and in case the simplification doesn't reduce enough it translates the symbolic amplitudes to simple digits (too keep a short label)
• fixed a couple of mistakes in the readme examples