Basic PHP7 compatibility

[moeffju]

All plugins etc. need to be converted to use HabariError instead of Error.

[moeffju]

I remember we looked at namespaces some time, but I can’t quite make heads or tails of the submodule structure.

[miklb]

I think this was done in the master branch, which is quite a divergence from 0.9.x

[moeffju]

That makes sense, but I guess we should maybe push out a release then? :)

[miklb]

I've actually been thinking about that, and I believe my comment was misplaced. This PR does make sense, and a release would also be appropriate.

Apologies for the confusion.

[iromeister]

Is there any hope for a PHP7 compatible release? No activity for 2 years now...

[Konzertheld]

@iromeister No, unfortunately there are no releases planned as there has been no development activity for quite a while. You can try this branch or even experiment with the master branch. The master branch is very experimental and differs widely from 0.9.2 but it is PHP 7 compatible.

If you try this branch successfully, let me know, I will then test it myself and could merge it afterwards.

Please make sure to do backups before testing either option.