There was another tool called General Edit (http://www.quadrivio.com/ge.html) which used to be available for the Mac but is now defunct. It was one of the inspirations behind Binspector and sounds very similar to the tool you mentioned.
Having wanted a binary grammar format for a while, and just purchased the Pro version of "Synalyze It!" as a starting point, it would be interesting to hear a short non-specialist's summary of the relative merits of your approach to expressing grammars compared with an XML based approach like "Synalyze It!" ...
Overall, "Synalyze It!" seems mostly fairly stable and certainly a useful tool well worth the purchase price for the Pro version. However, it is closed source, by a small developer, on a single platform: would much prefer to rely on something with source code available ...
Or, maybe a better question is what grammars are you currently using Synalyze It! for? I have used Binspector for fairly complex file formats and it has held up for my purposes in the past. Would it be worth an hour or two to see if Binspector could pass muster?
The grammars are for various 2D & 3D CAD model formats. Some can be fairly complicated, and the data files can be fairly large. For clarity, I'm bootstrapping something and don't have any immediate plans to open source the grammars.
Certainly, it would be worth looking at Binspector.
Probably it would take me a couple of days to get up to speed though, and that is not time that I have immediately.
It's not mentioned in the release note, but I find implementing "Mix commit notes with merge request notes on MR show page" (https://github.com/gitlabhq/gitlabhq/pull/1630) the greatest change in 3.0. We are using merge requests as a tool in code review, and this commit finally allow us to go through all comments of an MR in a single page. It would be perfect if the issue "Save few lines of code with Merge Request comment like github does" (https://github.com/gitlabhq/gitlabhq/issues/1007) is implemented, as this would allow us to finally reliably comment directly on the "diff" tab.
[1]: https://www.synalysis.net