Update vendored emoji.json

Updated to iamcal/emoji-data@4035824d56
add pending test placeholders for variation support

Did I miss anything?  In any point, this will give us a start.  Sadly
will need to do quite a bit to make sure we are handling all possible
permutations intelligently here.
add pending test for default output decision on `.char`
convert some pending tests to failing tests
test for another corner case
failing tests for the rest of the basics
implement `.variant` and `.variant?` for EmojiChar
implement EmojiData.all_with_variants
Implement `.all_doublebyte`

Convenience method to match `.all_with_variants`
Implement variant support in `.find_by_unified`

Matches to the proper parent EmojiChar object.

Added to hash map for fast lookups, the initialization of this is kinda
ugly and un-rubylike in syntax, look into making it nicer when it’s not
2am on a Friday night.

But does it work? Yes.
EmojiChar.to_s can output either variation or not
unified to char should pass directly through

since its a conversion method, don’t do a lookup, just convert based on
rules.  this means we won’t canonicalize in this case, but we probably
shouldn’t, people want to just be able to call and not have something
unexpected happen.

as part of this, also break the method out into a static class method
in EmojiChar so it can be reused.
add simplecov and coveralls for test coverage

help me figure out where I need to look at more closely when making
changes like this
code coverage badges in README

Almost unrelated to this PR, but since I already had this text in my
buffer from another repo, why not.
update .chars and .codepoints to be variant aware

won’t emit by default unless passed an option hash

NOTE: we lost memorization on these with this change, since they now
accept an arg.
fix .find_by_str for variant support

This one ended up being quite complex to support, and requires adding a
.chars method and a String mixin module to make the code easier to read
and keep it expressive.  Hopefully won’t cause a big performance
regression.
make sure there is always an instance var for variations

better workaround for inconsistency in iamcal/emoji-data#4

instead of wrapping the accessor, just make sure there is always an
empty instance var for `variations` during initialization, that way if
the value is missing from the JSON we don’t run into problems later
with other things that expect it to be there.
Update emoji data to iamcal/emoji-data@6cb685cd1e
increase known char count for :stars::speaker::train:
Make variant encoding the default for `char/to_s`

Change necessitates a few other changes, this is where test coverage
saves our asses.