Improve spec extraction

[kepper]

This is an almost complete rewrite of the code that generates the spec pages. It depends on music-encoding/music-encoding.github.io#62 for correct rendition. Please have a close look before this gets merged. All links should stay the same, except for Macro Groups (<macroSpec type="pe">), which are now in a separate folder. I think this is acceptable, as per discussion on #64. If accepted, this branch probably

• fixes add links from data-dictionary to guidelines #28
• fixes Invalid html in guidelines #47
• fixes Formatting in attribute class documentation #35
• fixes Missing symbols in <dir> #46
• fixes Make extractGuidelines.xsl less verbose #59
• fixes shall we split up macro groups from data types? #64

[ahankinson]

How did you test it? (More importantly, how can we test it, short of merging and fixing?)

[kepper]

well, it runs on my machine, and it works well here. I don't know if the pipeline on Github picks it up properly, but afaik, we're using a Saxon there as well, so it should be ok. If you download both branches and run extractGuidelines.xsl against the canonicalized4.0.0.xml in the same folder (which is just a recent local copy of the compiled MEI sources), you can then serve both repos locally using Jekyll. It takes a while to compile everything, but then you should get the new version running locally.

[ahankinson]

I've run it on my machine and it seems to work. We're going to need to trigger a new build, though, which I can do.