Some cells (e.g. $macc_v2) are marked evaluable, but will raise an abort if called with `CellTypes::eval()`.
Instead of falling through to the abort, we can pass a pointer to a boolean to check for errors.
Use said check to catch `CellTypes::eval()` errors and treat them as unevaluable but otherwise continue.
Reflows the series of if checks into `if ... else if ... else` so that we can check for errors and set state in one place.
Calling `throw dst_end_of_data_exception()` when the desired number of cycles has been reached means that the fst reader can't tidy up after itself and leads to memory leaks.
This doesn't happen when the `-stop` flag is used because the `Yosys::FstData` struct tracks the end time and skips the outer callback if the simulation has gone past the desired end time.
Move cycle checking into the inner callback along with the time checking means that the outer callback no longer needs to throw an exception in order to stop checking further values, while still allowing the fst reader to finish reading and deallocate memory.
libfst is no longer included in gtkwave and instead has its own repo. There has also been some refactoring, so the patches need to update to match, as does sim.cc.
Instead, change the default `Design::selected_modules()` to match the behaviour (i.e. `selected_unboxed_modules_warn()`) because it's a lot of files to touch and they don't really _need_ to be updated.
Also change `Design::selected_whole_modules()` users over to `Design::selected_unboxed_whole_modules()`, except `attrmap` because I'm not convinced it should be ignoring boxes. So instead, leave the deprecation warning for that one use and come back to the pass another time.
