Prepare for libtidy 5.6

[jokester]

@gagern Hello there. libtidy is targeting next 5.6 release to late November, so I made a branch in case we want to follow up. Will add more commits if I found necessary.

[jorrit]

5.6.0 has been released. I am wondering if a new release of node-libtidy could be created?

See https://github.com/htacg/tidy-html5/tree/master.

[gagern]

@jokester, feel free to turn that branch into a pull request. I'll have a look at it when I find the time. Hopefully this is a painless migration and opens the door for further improvements.

[adius]

Hey, what's the status on this?
Would be really cool to upgrade to 5.6.0! 😁

[prantlf]

@gagern, have a look at my PR #22, please. I based it on @jokester's work. I fixed some source files to continue working with tidy-html 5.6.0 in addition.

Names of option groups changed. See 5.4.0 and 5.6.0. It might be considered a breaking change.

[jokester]

Thanks @prantlf !!

[barhoumio]

Waiting @gagern merging your PR, here my npm that support node10 https://www.npmjs.com/package/node-libtidy

[cainrus]

Unable to build on my osx 10.13.4 machine:

➜ uname -a
Darwin mymachine.local 17.5.0 Darwin Kernel Version 17.5.0: Mon Mar  5 22:24:32 PST 2018; root:xnu-4570.51.1~1/RELEASE_X86_64 x86_64