Release 4.0.0 changelog

** [4.0.0] -2019-05-14
*** Documentation
**** Changed
- moved to sphinx and ReST
- merged HDL and software
- improved with examples
- doxygen and wbgen2 integration
**** Added
- Tools section
- Demo section
- Glossary section
*** Gateware
**** Changed
- soft-CPU is now uRV
- each core has a set of dedicated HMQ and RMQ
**** Added
- uRV debug interface
- notification interrupts from firmwares
- new test benches
*** Software
**** Changed
- synchronous messages redesigned
- HMQ API reflects gateware changes
- firmware library and framework improvements
- re-design Python wrapper a bit
**** Added
- driver auto-configuration from configuration ROM
- GDB agent to debug firmware
- tool to generated empty projects
- tools to interact with firmware framework
**** Removed
- Driver message filter
- LM32 support
- function to pause and start CPU execution
*** Demo
**** Added
- new demo section
*** Tests
**** Added
- new integration test section
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