QETLAB:Change log/v0.6

New functions

 * AbsPPTConstraints: Computes the linear matrix inequalities that determine whether or not a mixed state is "absolutely PPT".
 * Fidelity: Computes the fidelity of two quantum states, or allows the user to optimize over the fidelity of two quantum states in CVX.
 * InSeparableBall: Determines whether or not a given mixed state is within the ball of separability centered at the maximally-mixed state.
 * IsAbsPPT: Determines whether or not a mixed state is "absolutely PPT".
 * MaximumOutputFidelity: Computes the maximum output fidelity of two quantum channels.
 * XORClassicalValue: Computes the classical value of a two-player nonlocal XOR game.
 * helpers/superoperator_dims: Computes the input, output, and environment dimensions of a superoperator. Introduced in order to clean up the code in many other functions.

Changes to existing functions

 * BrauerStates: Reversed the order of the input arguments D</tt> and P</tt>.
 * CBNorm</tt> and DiamondNorm</tt>: Updated the script so that it can now also be used in the objective function or constraints of other CVX optimization problems (so you can minimize the diamond norm of all channels satisfying a given linear constraint, for example).
 * Entropy</tt>: Now has a second optional input argument, ALPHA</tt>, which allows the user to compute arbitrary Renyi entropies, rather than just the usual von Neumann entropy.
 * Pauli</tt>: Now allows the user to request a several-qubit Pauli operator, rather than just a 1-qubit Pauli operator. Also, this function now returns output that is sparse by default, rather than full.
 * Swap</tt> and SwapOperator</tt>: Reversed the order of the SYS</tt> and DIM</tt> optional input arguments.
 * Twirl</tt>: Can now also perform Pauli twirls.