The latest verion of iverilog enforces declaration ordering more
strictly. Update a few test cases to match. sv2v still supports
out-of-order items on a best-effort basis.

I'm opting for iverilog's interpretation of the specifications here. The
commercial simulators I tested seem to agree.

Co-authored-by: qcorradi <q.corradi22@imperial.ac.uk>
Co-authored-by: Zachary Snow <zach@zachjs.com>

* Remove unneeded begin/end when the loop is a do/while
* Dangling else check passes through statement attributes (bug fix)
* Dangling else check passes through most control flow structures to reduce unneeded begin/end
* Add test case and update changelog

---------

Co-authored-by: qcorradi <q.corradi22@imperial.ac.uk>
Co-authored-by: Zachary Snow <zach@zachjs.com>

* Fixing a bug where always_* are not converted when attributed
* Added tests and updated Changelog for the attributed always_* fix

- The deleted chunk in TFBlock has been unreachable since 57ef23ef. The
  RemoveComments change would make it reachable by dropping the leading
  Null in a task or function body.
- The optimization in TFBlock was unsound because the nested block could
  shadow identifiers used (but not defined) in the tail of the outer
  block.
- The optimization is not clearly necessary, so I'm dropping it for now.
- Expand tf_block test coverage.

- test deprecated flags
- test struct const edge cases
- test implicit net edge cases
- test dump-prefix

- fold string literal comparisons
- fold non-decimal bit shifts
- fold non-decimal integer comparisons
- fold decimal bitwise AND and OR
- simplify cast expressions before elaboration
- remove duplicate cast expression traversal
- flatten concatenated numbers in a single pass