added function for creating controlled versions of arbitrary single-qubit gates
Merge pull request #135 from jrjohansson/controlled-gates

added function for creating controlled versions of arbitrary single-qubit gates
Merge pull request #136 from anubhavvardhan/add_gates

Added CSIGN, SWAPalpha and Berkeley gates and simplified base case of other gates
added support for latex rendering of swap gate symbol
qdjusted arg_label for CPHASE gates in qft_gate_sequence
improved gate label formatting
allow reversing the circuit represenation. added support for multigate symbol
Merge pull request #137 from jrjohansson/QubitCircuit-extension

Qubit circuit extension
Added unitary matrix calculator for arbitrary qubit circuit
Added more gate labels
Added function to calculate gate sequence product
Used added function to calculate gate sequence product
Removed bug from circuit.py
Removed bug from gates.py
Merge pull request #138 from anubhavvardhan/quantum_circuit

Added unitary matrix calculator for arbitrary qubit circuit
Removed bug from berkeley function
Added import statement for gates
Merge pull request #139 from anubhavvardhan/quantum_circuit

Bug Fixes
Changed target & control to targets[] in swap gates
Changed call parameters in swap gates