v2.1.0 Release

Release 2.1.0. Updates include:

• Added chowdsp_visualizers module.
• Added chowdsp_presets_v2 module.
• Added chowdsp::StringLiteral.
• Added chowdsp::buffer_iters.
• Added chowdsp::AdditiveOscillator.
• Added chowdsp::ThreeWayCrossoverFilter.
• chowdsp::Gain: Fixed reset() to reset the smoother to the target gain value.
• BypassProcessor: Added template specialization with no latency compensation.
• chowdsp::BufferMath: Added multiplyBufferData() function.
• chowdsp::BufferView: Added constructor for 1d-array.
• chowdsp::LinearPhaseEQ: Prototype EQs must now define their floating point type.
• Moved Version to chowdsp namespace, and made constexpr-able.