Guide.manual_discrete_key

[Mattriks]

• I've updated the documentation to reflect these changes
• I've added an entry to NEWS.md
• I've added and/or updated the unit tests
• I've run the regression tests
• I've built the docs and confirmed these changes don't cause new errors

This PR:

• adds Guide.manual_discrete_key
• Guide.manual_color_key is updated with new features (e.g. pos, shape, size)

Example

using DataFrames, RDatasets
points = DataFrame(index=rand(0:10,30), val=rand(1:10,30))
line = DataFrame(val=rand(1:10,11), index=collect(0:10))
p1 = plot(layer(points, x=:index, y=:val, color=[colorant"green"]),
    layer(line, x=:index, y=:val, Geom.line),
    Guide.manual_color_key("Legend", ["Points", "Line"], ["green", "deepskyblue"],
        shape=[Shape.circle, Shape.hline]))

D = dataset("COUNT", "titanicgrp")
D = join(D, by(D, :Class, :Cases=>sum), on=:Class)
D.prcnt = 100*D.Survive./D.Cases_sum 
p2 = plot(stack(D, [:Age, :Sex]), xgroup=:Class,
    Geom.subplot_grid(Guide.xlabel(orientation=:horizontal),
        layer(x=:variable, y=:prcnt, color=:value, Geom.bar),        
    ),  Scale.x_discrete, Guide.ylabel("Survival (%)"),
    Guide.manual_color_key("Age", ["children","adults"], 1:2),
    Guide.manual_color_key("Sex", ["women","men"], 3:4),
    Theme(bar_spacing=1mm, key_position=:none, 
        key_swatch_shape=Shape.square, point_size=4pt))
hstack(p1, p2)

[codecov-commenter]

Codecov Report

Merging #1441 into master will decrease coverage by 0.04%.
The diff coverage is 88.37%.

@@            Coverage Diff             @@
##           master    #1441      +/-   ##
==========================================
- Coverage   89.42%   89.37%   -0.05%     
==========================================
  Files          39       39              
  Lines        4369     4378       +9     
==========================================
+ Hits         3907     3913       +6     
- Misses        462      465       +3     

Impacted Files	Coverage Δ
src/guide.jl	90.48% <ø> (+1.26%)	⬆️
src/theme.jl	65.07% <ø> (ø)
src/guide/keys.jl	82.69% <88.09%> (+0.87%)	⬆️
src/poetry.jl	90.74% <100.00%> (ø)
src/statistics.jl	96.44% <0.00%> (-0.58%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 44d9ca8...cc9539c. Read the comment docs.

[Mattriks]

Tests pass, but getting an error in the doc build (not due to docs).