feat: Turtle.get/set_ViewBox ( Fixes #30 )

Author: James Brundage

Types/Turtle/get_ViewBox.ps1

@@ -0,0 +1,7 @@
+if ($this.'.ViewBox') { return $this.'.ViewBox' }
+$viewX = $this.Maximum.X + ($this.Minimum.X * -1)
+$viewY = $this.Maximum.Y + ($this.Minimum.Y * -1)
+
+return 0, 0, $viewX, $viewY
+
+

Types/Turtle/set_ViewBox.ps1

@@ -0,0 +1,31 @@
+param(
+[double[]]
+$viewBox
+)
+
+if ($viewBox.Length -gt 4) {
+    $viewBox = $viewBox[0..3]
+}
+if ($viewBox.Length -lt 4) {
+    if ($viewBox.Length -eq 3) {
+        $viewBox = $viewBox[0], $viewBox[1], $viewBox[2],$viewBox[2]
+    }
+    if ($viewBox.Length -eq 2) {
+        $viewBox = 0,0, $viewBox[0], $viewBox[1]
+    }
+    if ($viewBox.Length -eq 1) {
+        $viewBox = 0,0, $viewBox[0], $viewBox[0]
+    }
+}
+
+if ($viewBox[0] -eq 0 -and 
+    $viewBox[1] -eq 0 -and 
+    $viewBox[2] -eq 0 -and  
+    $viewBox[3] -eq 0
+) {
+    $viewX = $this.Maximum.X + ($this.Minimum.X * -1)
+    $viewY = $this.Maximum.Y + ($this.Minimum.Y * -1)
+    $viewBox = 0, 0, $viewX, $viewY    
+}
+
+$this | Add-Member -MemberType NoteProperty -Force -Name '.ViewBox' -Value $viewBox