Add ids to definitions for linking

[JimPatterson]

We use the deflist to create a glossary and need to link to specific definitions.

I ran unittest and they fail on the branch upstream master branch. I did not attempt to correct that, but I did fix the tests relative to these changes so they don't fail any more than they did.

[JimPatterson]

The travis test fails due to trying to use a really old version of node that is not compatible with the current versions of the tools. Do we need to stay with such an old version of node?

[puzrin]

@JimPatterson thanks for suggestion. I'm very conservative about adding new options, because this process is endless and very opinion-based. So, default answer is "no to everything if possible". In details - i check first, if the same effect can be acheived without upstream change.

Also note, in your current solution it's very easy to create conflicting ids, if user uses deflist twice (or create quote of deflist on the same webpage).

IMO, in this case, you could get the same result via customized renderer methods, without dependency on my personal opinion.

BUT... if you have explanation why all dt MUST have id, i'm ready to learn.

To be honest, similar issues about head ancors stays unresolved for a long time markdown-it/markdown-it#28, and i doubt we can find good deflist-specific solution in reasonable time.

The travis test fails due to trying to use a really old version of node that is not compatible with the current versions of the tools. Do we need to stay with such an old version of node?

It breaks due unpinned dependency versions, i'll fix both a bit later, don't worry about travis status.

[JimPatterson]

@puzrin I'm okay with rejecting this, I'll use the other interface for my projects needs.