Add name to statemachine and make dot output stable and unique

[asmfreak]

This adds ability to name statemachines. I have a personal pet project that uses smlang.
It uses several ones of them. So I wanted to see them all as pictures via graphviz.
My problem with that was: smlang-rs generates only one picture (statemachine.svg).
Also I wanted to give each statemachine a unique name.
This patch addresses both issues.
I've also bumped the version as this change is a bit significant in my opinion. Please advise, if it should be revised.

[ryan-summers]

Sorry for the late review - was on vacation the last two weeks :)

Please also:

• Note this as a change in the CHANGELOG.md

[asmfreak]

I've implemented proposed changes.
I've also added derive functionality to states and events. Since it was conflicting with other feature (impl_display), I completely removed code for it, since the derive version has a broader scope.

[ryan-summers]

LGTM, just needs to have a run of cargo fmt to fix up style. One optional change requested below, but I won't block merging off that.

Thanks for taking the time on this!

[ryan-summers]

Looks like some tests are also failing

[ryan-summers]

Thanks for pushing through on this :)