Directly subclassing Iterable is lazy-ish, but if you call any operation
on the resulting value (eg. map or ++) it will evaluate the Iterable and
return a List.

Transformation of mem readwriters whose address contain references to
readwriters of mems declared before it would contain invalid references
to untransformed memory readwriter, as the connection is not transformed.
This commit fixes this issue.

This will make it easier to compile circuits with
older compiler versions.

* [smem] fix read-under-write serialization

Also adds some tests for the parser and
the serializer.

* Serializer: always serialize smem ruw behavior

* test: simplify smem test circuit

* allow for zero-width integer literals
* CheckWidths: ensure that width is non-negative

Also get rid of whitespace-only lines that were emitted after every when
block.