Automatically enable ANSI colours on Windows versions that support it

Note that stream_isatty() and sapi_windows_vt100_support() are ONLY defined on PHP 7.2, and the latter is only available on Windows.

start.ps1

@@ -25,7 +25,7 @@ if(Test-Path "PocketMine-MP.phar"){
 }
 
 function StartServer{
-	$command = "powershell " + $binary + " " + $file + " --enable-ansi " + $extraPocketMineArgs
+	$command = "powershell " + $binary + " " + $file + " " + $extraPocketMineArgs
 	iex $command
 }