add timezone support

[touletan]

Add moment-timezone module to support timezone in time scale
proposed solution to fix this:
Timezone support

Codepen Example

[phbou72]

Would be nice to have this merged!

[etimberg]

It won't let me comment on the file, but it looks like Chart.js is now a submodule of itself. :|

[touletan]

required fix has been applied

[etimberg]

I am ok with the functionality. @benmccann @simonbrunel are you ok with this and bringing in a new dependency?

[touletan]

.

[benmccann]

Sorry I'm taking awhile to review this. I want to give it really deep thought and do plan to take a look

[benmccann]

@touletan I really appreciate the hard word you've put into this PR. I've been spending a lot of time digging into this during the past week trying to ensure we take the best path forward. My main concern is that we already get a lot of complaints about how big moment is and it appears that moment-timezone is even larger. It's a really big dependency to be adding and so I don't think it's a good idea to add moment-timezone to Chart.js because of the size.

I reached out to one of the maintainers of moment after coming across their blog while researching possible paths forward and they suggested we might want to consider the new Moment project Luxon: http://moment.github.io/luxon/.

The issue with switching to Luxon is that it is not backwards-compatible. If possible, it would be nice if we didn't leak our usage Moment into our APIs, so that we could make internal changes that users need not be aware of. However, given the situation we are into today I think perhaps this might have to wait until 3.0.0.

Thoughts @etimberg @simonbrunel ?

[etimberg]

I'm OK with trying out moving to Luxon. Not sure if we want the next version to be 3.0 or not. @simonbrunel what are your thoughts?

[etimberg]

Closing due to inactivity

[benmccann]

I've created issue #5186 to consolidate the various pieces of feedback we've received regarding time zone support. Please feel free to subscribe to it for updates