Release 0.7.3

Added

• Documentation: GitHub pages.
• Linters: .clang-format and .clang-tidy.
• Integrate with libqasm 0.6.8 release:
  • Add gate modifiers. Notice though that pow only works with integer exponents.

Changed

• Implement instructions as a hierarchy.
• Implement GateConvertor as a CircuitBuilder.
• Implement BasisVector as a boost::dynamic_bitset<uint32_t>.
• Implement RegisterManager as a singleton.
• Change QuantumState by taking the measurement register out of it.
• Change Circuit::execute to return a SimulationIterationContext.
• Change Matrix and DenseUnitaryMatrix to use std::vector instead of std::array.
• Change file, functions, and variable names.

Removed

• abseil library dependency.