Cpp Stm Free Versions Save

'Stupid GUID' replaced by int. Boost x2 in single threaded, x10 in multithreaded.

• New engine: Church-encoded Free monad instead of Free monad. Both engines are available, but Church is now main.
• New engine: optimization. Quadratic complexity of binding is eliminated. Now, it's linear.
• New project structure.
• std::optional-aware STML combinators.
• More new combinators.
• Several small optimizations and tunings.

• License changed to BSD 3.
• Removed dependency from cpp_functional_core.
• Code structure improved and cleaned up.
• Unused stuff removed.
• Combinators interface updated.
• Small fixes and improvements.

• Code cleanups
• New combinators
• Tiny behavior improvements

First working version of STM with free monad.

• Monadic STM: core mechanics
• Combinators
• Simple Context

• Concurrency bug fixed. Now, only modified TVars would be merged on commit.
• Tiny performance improvements.