Design medium-level abstractions for smart contracts - Fleetwood™ about ink

[Robbepop]

Commit 64aa222 implements the foundations for the upcoming medium level abstractions inspired by Fleetwood.

Visit https://github.com/Robbepop/pdsl/tree/master/model/examples for some not yet completely working examples. Note that this is very experimental and very unstable.

Visit https://github.com/Robbepop/pdsl/tree/master/model/ for a general overview of the new crate.

[Robbepop]

Commit 1d9bb5f and the few previous implement some of the final things that have been missing. This represents a very raw and still majorly untested implementation of the Fleetwood abstractions.

Also they are not recommended to be used since they lack proper compile-time functionality for critical parts and still do not produce automatic message selectors; instead the user has to define them themselves which is far from an optimal user experience.

[Robbepop]

Some future enhancements:

• Only flush the state if the called message was possibly mutating it. So calling a message that was not registered as mut shall not require to flush the state after its call. Note that this is already done halfway through the pdsl_core since it will itself only flush state that could have been possibly mutated. However, in the pdsl_model we can still optimize this to avoid the call to flush in statically.

[Robbepop]

Since all of this has been implement long ago and is considered to be stable (enough) I am going to close this now.