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
Added CSIGN, SWAPalpha and Berkeley gates and simplified base case of other gates
Changed control1&2 to list of controls in fredkin and toffoli
Merged control variables into a single list for gate expand 3 to n
Modified unit test for test_gate to use controls list
changed default value of controls list
fixed bug in gates.py
bug fix in gates.py
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