Remove underscore from observe sequence

[harryadel]

As I'm wrapping up meteor/meteor#11869 Test Group 3 is failing because it runs non-core packages and observe-sequence requires underscore which is no longer around since now it's now deprecated. There's no need for publishing a new version of Blaze or Observer-sequence; this PR just needs to be merged in dev branch so in meteor repo the latest commit can pulled. Coincidentally, I'm glad the the underscore removal was done here first as it'd not have worked if it had been done in Meteor repo first. 😅

[StorytellerCZ]

LGTM
We should still release a patch version of this package or include it in the next release independent of what is happening in the Meteor repo.

[StorytellerCZ]

Let's merge this into 2.6 release and release 2.6. What do you think @filipenevola ?

[fredmaiaarantes]

LGTM

[harryadel]

Any update on this and the 2.6 release? @StorytellerCZ @renanccastro @filipenevola

[StorytellerCZ]

@fredmaiaarantes @jankapunkt let's include this in 2.6?

[jankapunkt]

I would generally add it to 2.6 but I'd like to discuss one more this PR (see my comment on the code).

If this is to be a showstopper (due to further discussion) then we might publish 2.6 with this PR as-is and move the final removal of lodash (see my comment on the code) to 3.0?

[StorytellerCZ]

@harryadel can you please address @jankapunkt comment? Then we can merge this into 2.6 and release.

[harryadel]

Right away!

[StorytellerCZ]

@harryadel this seems to be the issue of the failing tests:

TypeError: posNew.forEach is not a function
    at diffArray

[harryadel]

It's weird that some errors weren't caught by the CI before 🤔