With pretty parse errors on failures. The type-checker was already
implemented for those, so it now only requires some work in the code
generation.
Fixes#297.
This possibly breaks many Aiken programs out there, but it's for the
best. We haven't released the alpha yet so we still have a bit of
freedom when it comes to breaking change.
Plus, the migration path is easy, simply run:
```
find . -name "*.ak" | xargs sed -i "s/#(/(/g"
```
(or `-i ''` on MacOS).
* add unary op
* parse, typecheck, and code gen it
* express boolean not as unary op as well, previously called negate
Co-authored-by: rvcas <x@rvcas.dev>
rvcas