WP2005 - Codec 2 Algorithm Description

[drowe67]

A document describing how Codec 2 works

• [x] High level description using block diagrams and figures, average Ham level audience. This could be broken out for articles.
• [x] Maths based description
  • [x] pitch estimation
  • [x] sinusoidal analysis
  • [x] voicing estimator
  • [x] sinusoidal overlap add synthesis
  • [x] LPC/LSP quantisation
  • [x] newamp1 quantisation
  • [x] post filtering
  • [x] further work for document
• [x] Makefile or script to build doc, figures
• [ ] github action to make sure we can keep building doc (should this be part of ctests?)

Deliverables

1. Latex doc
2. Merge PR