tr-TR culture problem fix #1095

Author: alatas

Engine/Settings.cs

@@ -395,7 +395,7 @@ private void parseSettingsHashtable(Hashtable settingsHashtable)
             var settings = GetDictionaryFromHashtable(settingsHashtable);
             foreach (var settingKey in settings.Keys)
             {
-                var key = settingKey.ToLower();
+                var key = settingKey.ToLowerInvariant();
                 object val = settings[key];
                 switch (key)
                 {

Tests/Engine/SettingsTest/Issue1095/Issue1095.tests.ps1

@@ -0,0 +1,20 @@
+Describe "Issue 1095: An exception is thrown when CurrentCulture is Turkish (tr-TR)" {
+    It "Should not throw an exception when CurrentCulture is tr-TR" {
+        # https://github.com/PowerShell/PSScriptAnalyzer/issues/1095
+
+		$initialCulture = Get-Culture
+        $initialUICulture = Get-UICulture
+
+        {
+            $trTRculture = [System.Globalization.CultureInfo]::GetCultureInfo('tr-TR')
+            [System.Threading.Thread]::CurrentThread.CurrentUICulture = $trTRculture
+            [System.Threading.Thread]::CurrentThread.CurrentCulture = $trTRculture
+            Invoke-Formatter "`$test" -ErrorAction Stop
+
+        } | Should -Throw -Not
+
+        [System.Threading.Thread]::CurrentThread.CurrentCulture = $initialCulture
+        [System.Threading.Thread]::CurrentThread.CurrentUICulture = $initialUICulture
+       
+    }
+}