feat: Turtle method chaining ( Fixes #22 )

Returning $this

Author: James Brundage

Types/Turtle/Clear.ps1

@@ -1,3 +1,4 @@
 $this.Position = 0, 0
 $this.Heading = 0
-$this.Steps = @()
+$this.Steps = @()
+return $this

Types/Turtle/Forward.ps1

@@ -7,3 +7,4 @@ $x = $Distance * [math]::round([math]::cos($this.Heading * [Math]::PI / 180),15)
 $y = $Distance * [math]::round([math]::sin($this.Heading * [Math]::PI / 180),15)
 $this.Position = $x, $y
 $this.Steps += "l $x $y"
+return $this

Types/Turtle/L.ps1

@@ -44,4 +44,4 @@ foreach ($character in $finalState.ToCharArray()) {
         }
     }
 }
-return
+return $this

Types/Turtle/Rotate.ps1

@@ -5,4 +5,5 @@
     Rotates the turtle by the specified angle.
 #>
 param([double]$Angle = 90)
-$this.Heading += $Angle
+$this.Heading += $Angle
+return $this

Types/Turtle/SierpinskiTriangle.ps1

@@ -11,3 +11,4 @@ $this.L('F-G-G',  [Ordered]@{
     '-'     = { $this.Rotate($Angle * -1) }
     '[FG]'  = { $this.Forward($Size) }
 })
+return $this

Types/Turtle/Square.ps1

@@ -2,4 +2,5 @@ param([double]$Size = 50)
 foreach ($n in 1..4) {
     $this.Forward($Size)
     $this.Rotate(90)
-}
+}
+return $this