Implement visualization for ALMA

>Legoux claimed the ALMA moving average was inspired significantly by
>the Gaussian Filter and often compares his developed moving average
>to the Hull Moving Average (HMA), which is said to be outperformed by
>the ALMA in effectiveness and smoothness.

I love the Hull Moving Average, so I had to see what ALMA had to offer.
My initial impression is positive.

README.md

@@ -77,7 +77,7 @@ golden_cross_chart |> visualize |> lwc_show
 
 - [ ] AccuDist
 - [ ] ADX
-- [ ] ALMA
+- [x] [ALMA](https://www.tradingview.com/support/solutions/43000594683-arnaud-legoux-moving-average/)
 - [ ] AO
 - [ ] Aroon
 - [x] [ATR](https://www.tradingview.com/support/solutions/43000501823-average-true-range-atr/)

src/ALMA.jl

@@ -0,0 +1,23 @@
+denominated_price(alma::ALMA) = true
+
+"""$(TYPEDSIGNATURES)
+
+Return an lwc_line for visualizing an ALMA indicator.
+"""
+function visualize(alma::ALMA, opts::Union{AbstractDict,Nothing}, df::DataFrame)
+    name = indicator_fields(alma)[1]
+    start = findfirst(!ismissing, df[!, name])
+    kwargs = Dict(
+        :label_name => "ALMA $(alma.period)",
+        :line_color => "#5B9CF6",
+        :line_width => 2
+    )
+    if opts !== nothing
+        merge!(kwargs, opts)
+    end
+    return lwc_line(
+        df.ts[start:end],
+        [df[!, name][start:end]...];
+        kwargs...
+    )
+end

src/TechnicalIndicatorCharts.jl

@@ -485,6 +485,7 @@ function visualize(chart::Chart;
     )
 end
 
+include("ALMA.jl")
 include("ATR.jl")
 include("BB.jl")
 include("DEMA.jl")

test/ALMA.jl

@@ -0,0 +1,18 @@
+using TechnicalIndicatorCharts
+
+@testset "ALMA" begin
+    if !isdefined(Main, :sample_candles)
+        include("helper/main.jl")
+    end
+    chart = Chart(
+        "TEST", Minute(1),
+        indicators=[ALMA{Float64}(;period=5)],
+        visuals=[nothing]
+    )
+    candles = sample_candles()
+    for c in candles
+        update!(chart, c)
+    end
+    @test visualize(chart) isa Any
+    # If it gets this far, we can instantiate, update, and visualize.
+end