Spatializer (`spatializer.cpp`) Enhancements: Advanced Reverb Algorithm

[BennyPerumalla]

• Pre-Delay: Introduce a dedicated pre-delay parameter to control the time between the dry signal and the onset of reverberation, a critical component for simulating realistic spaces.

• Room Size Control: Implement a "Room Size" parameter that scales the FDN's internal delay line lengths, allowing for a continuous transition from small, tight rooms to large, cavernous spaces.

• Stereo Reverb Input/Output: Evolve the FDN to process a true stereo input (e.g., feeding L/R channels to different delay lines) and use more sophisticated output tapping to create a more immersive and stable stereo reverb image.

• Improved Diffusion: For a richer, more colorless reverb tail, the FDN's static Hadamard matrix could be replaced with a more effective unitary matrix (e.g., a Householder matrix) to improve diffusion.

open for discussion