Add support for multi-data tooltips

[noahrhodes]

Setting tooltips for multiple components was not working (see #332)

augument_encoding_type did not run correctly for an array that was passed in as the tooltip information.

this change adds augment_encoding_type(x::Array, data::Vega.DataValuesNode) for array types. It takes arrays and runs augment_encoding_type on the internal components

This code snippet now works:

using VegaLite, VegaDatasets

iris = dataset("iris")|>
@vlplot(
    tooltip=[{field="species"},{field="sepalLength"}],
    data=iris,
    :point,
    x=:petalWidth,
    y=:petalLength,
    color=:species,
)

There is a line in the docs/src/examples/examples_table_based_plots.md that can be updated if this change is added #tooltip=[{field="Origin",type="nominal"},{field="Cylinders",type="quantitative"}] #array not supported

This is my first contribution to the package. Is there anything else I should add to this pull request?
This fixes the problem and passes the tests, but I am unsure if there are other implications. This may not even be the correct way to fix this problem, and I am happy to take pointers to a different approach.

[davidanthoff]

Awesome, that does look correct to me!

Could you maybe add a test that exercises this new code path?

I think eventually we would probably also want a simple =[:foo, :bar] to work, but we can do that in a follow-up PR.

[codecov-commenter]

Codecov Report

Merging #382 (5e6ad7c) into master (28c9ad9) will increase coverage by 2.01%.
Report is 50 commits behind head on master.
The diff coverage is 77.27%.

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@@            Coverage Diff             @@
##           master     #382      +/-   ##
==========================================
+ Coverage   76.90%   78.92%   +2.01%     
==========================================
  Files          12       12              
  Lines         433      427       -6     
==========================================
+ Hits          333      337       +4     
+ Misses        100       90      -10     

Flag	Coverage Δ
unittests	78.92% <77.27%> (+2.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files Changed	Coverage Δ
src/VegaLite.jl	100.00% <ø> (ø)
src/vlspec.jl	77.63% <40.00%> (-2.66%)	⬇️
src/rendering/show.jl	76.92% <88.23%> (+11.92%)	⬆️

... and 3 files with indirect coverage changes

[noahrhodes]

Changes made:

• Removed println statements
• Changed ::Array to ::AbstractArray
• Added a test for the code path
• Updated docs example to use array instead of a calculation for hover text

As for the test, I wasn't sure what to really test, or where to put it. I added a test that ran a @vlplot macro with tooltip array, and checked that the tooltip encoding is an array.

I think eventually we would probably also want a simple =[:foo, :bar] to work, but we can do that in a follow-up PR.

It works just fine as is!

Let me know if there are any further changes to be made!

[noahrhodes]

Would it be possible to review and merge this sometime in the near future? It obviously hasn't been urgent, but a new issue was created about (#415) multiple field tool-tips.

[rtedwards]

Bump on this PR. Would love to see this merged. @noahrhodes @davidanthoff