feat: Turtle.TwinDragonCurve ( Fixes PoshWeb#35 )

Author: James Brundage

Types/Turtle/TwinDragonCurve.ps1

@@ -0,0 +1,38 @@
+<#
+.SYNOPSIS
+    Generates a Twin Dragon Curve.
+.DESCRIPTION
+    Generates a Twin Dragon Curve using turtle graphics.
+.LINK
+    https://en.wikipedia.org/wiki/Dragon_curve#Twindragon
+.EXAMPLE
+    $turtle.TwinDragonCurve().Pattern.Save("$pwd/TwinDragonCurve.svg")
+.EXAMPLE
+    $turtle.Clear()
+    $turtle.TwinDragonCurve(20,7,90)
+    $turtle.PatternTransform = @{
+        'scale' = 0.9
+        'rotate' = 45
+    }
+    
+    $turtle.PatternAnimation = "
+    <animateTransform attributeName='patternTransform' attributeType='XML' type='scale' values='1;0.9;1' dur='19s' repeatCount='indefinite' additive='sum' />
+    <animateTransform attributeName='patternTransform' attributeType='XML' type='skewY' values='30;-30;30' dur='67s' repeatCount='indefinite' additive='sum' />
+    <animateTransform attributeName='patternTransform' attributeType='XML' type='skewX' values='30;-30;30' dur='83s' repeatCount='indefinite' additive='sum' />
+    "
+    $turtle.Pattern.Save("$pwd/TwinDragonCurve2.svg")
+#>
+
+param(
+    [double]$Size = 20,
+    [int]$Order = 6,
+    [double]$Angle = 90
+)
+return $this.L('FX+FX+',  [Ordered]@{
+    X = 'X+YF'
+    Y = 'FX-Y'
+}, $Order, [Ordered]@{
+    '\+'    = { $this.Rotate($Angle) }
+    '-'     = { $this.Rotate($Angle * -1) }
+    '[F]'  = { $this.Forward($Size) }
+})