Removing existing options in favor of the renderer

[chjj]

We have the opportunity to remove:

• highlight
• langPrefix
• headerPrefix
• heading IDs

In favor of the new renderer.

The downside to this (at least for 3 of them): lack of backward compatibility, and less convenience for users used to marked. While I did merge the renderer, I'm tentatively reimplementing a few of these options. I think the removal of these features should be discussed in another issue because it is a big decision.

cc @lepture

[lepture]

marked is still on the early stage. It has not released 1.0.0 yet. I think it will be ok for these big changes.

1. headerPrefix and heading IDs doesn't worth the options (I thought)
2. block highlight is ok with renderer. however, there is a discussion on async highlight in #301

[jonathanong]

i'd prefer less features, more extensibility. i'm +1 to removing all those options.

[lepture]

@chjj I am wondering why you revert the changes.

[birendra-ideas2it]

how to give blockquote regular expression like slack?