Add zero-copy deserialization

[SergioBenitez]

This effectively rebases #208 on the current tip and fixes up some, but certainly not all, of the issues I spotted along the way. The html5 test is not passing (I'm not sure why it expects bad utf-8?) and neither are the tests that were previously commented out which I assume means they weren't passing then, either.

I'd love to see this merged. I won't have futher time myself to continue working on this, but I thought I'd nudge it in the right direction. I've given @andreivasiliu commit access to the fork and the owners of this repository have access as well. Feel free to work in the fork or take this work and fork it itself and PR - whatever. Also don't feel the need to maintain my authorship of this PR in any way. Please do quite literally whatever you wish with this.

[SergioBenitez]

Is there interest in this?

[dralley]

I expect there is, he's just been inactive for a few weeks (not a criticism)

[tafia]

Sorry for the long delay in answering. I have reviewed it and I am not sure I understand it all so I didn't want to merge too quickly ... then life happened. I'll to it this week

[tafia]

Alright after far too many months, I have finally reviewed this PR.

Thanks SO MUCH for this work, there is not much to say. I have rebased it on current master and made tiny cosmetic modifications.

[tafia]

I'll probably make a new version very soon in case you're still interested.

[Mingun]

@tafia, you probably need to merge PRs more carefully, because this one was badly merged with the master and broke compilation. Also, it is quite big and not very well structured -- I don't know what else it can break.

I've fixed compilation in the #302

[dralley]

To be fair, it looks like the Github CI is broken, silently. As in the jobs failed (to run) without any warning on the PR, just a green check mark that said "no conflicts".

That's a huge UX issue on the part of Github, and I think the problems (the compilation failure at the very least) would have been pretty obvious if not for that.

@tafia Thank you for spending some time to get things reviewed and merged