Added Angular (text.html.ng) support

[egesu]

It already works when I put text.html.ng in additional grammars, however I thought this option is for optional extensions like backend languages. text.html.ng is always a frontend code, and no problem to put it in defaults.

By the way, text.html.ng is from language-html-angular package.

[liuderchi]

@egesu additional grammars is not designed for backend languages only;
it's a flexible, experimental config for grammars supported by community packages.
By doing so we keep scope of ide-html not too big.

IMO suitable config for text.html.ng is either

• additional grammars (experimental feature)
• or as a checkbox with description if it's really convenient for angular developers.

---

How do you think ---

• adding angular support as a checkbox config here
• adding description about requirement for this config: package language-html-angular
  • e.g. you need to install language-html-angular to apply text.html.ng grammar support
  • by doing so a new comer can understand whether he or she needs to toggle the checkbox.

[liuderchi]

@egesu any feedback to my comments?

[egesu]

Sorry about the delay. Additional grammars solves the issue very well, however the problem is when I wanted to use this feature, I had to find the grammar name for language-html-angular package. I didn't know anything about the grammars before, so I had to spend some time on it. Probably for a newbie in web development, additional grammars won't solve the issue. So I think checkbox would be nice.

I will update the PR as soon as possible.

[liuderchi]

... So I think checkbox would be nice.

@egesu That sounds Great!

IMO the description need to be informative by telling user that
this checkbox requires atom package language-html-angular