Fix fatal error with x values in reverse order

[jimmythai]

Issue Link 🔗

• ScatterViewChart entries hide when zooming #2884
• Scatter circle disappear when chart scaled #3185

Goals ⚽

Fixing the issues above and bugs as follows. Those bugs happen on BarChartViewController when you set entries which have x values in reverse order. A fatal error occurs on BubbleChartViewController, CandleStickChartViewController, LineChart1ViewController and ScatterChartViewController when you do the same things.

Implementation Details 🚧

Arrays of ChartDataEntry should be sorted in an ascending order when you initialize ChartDataSet and whenever you set them again, for instance, using replaceEntries(_:).

Testing Details 🔍

[codecov-io]

Codecov Report

Merging #4027 into master will decrease coverage by <.01%.
The diff coverage is 33.33%.

@@            Coverage Diff             @@
##           master    #4027      +/-   ##
==========================================
- Coverage   40.14%   40.13%   -0.01%     
==========================================
  Files         119      119              
  Lines       13985    13987       +2     
==========================================
  Hits         5614     5614              
- Misses       8371     8373       +2

Impacted Files	Coverage Δ
...s/Data/Implementations/Standard/ChartDataSet.swift	39.51% <33.33%> (-0.28%)	⬇️

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[liuxuan30]

I wonder if it's our job to sort the array, or let the user handle it? @jjatie @petester42

[xymtek]

sorting every-time the data is updated seems expensive. Maybe having some validation when drawing the next x should check if its larger than the previous x would be better.