Fix random.randint() with negative numbers

lib/compiling/GScompiler.js

@@ -67,7 +67,7 @@ Move new files to glowscript source:
 6) Copy the file embed/rapydscript.js to lib/rapydscript/compiler.js and insert this at start of file:
 
 In compiler.js you may need to replace the randrange machinery with this, though this is now in the RapydSript repo:
-# unlike the python version, this DOES build a range object, feel free to reimplement\ndef randrange():\n    if arguments.length is 1:\n        return randbelow(int(arguments[0]))\n    start = int(arguments[0])\n    stop = int(arguments[1])\n    if arguments.length < 3:\n        step = 1\n    else:\n        step = int(arguments[2])\n    width = stop - start\n    if step is 1:\n        if width > 0:\n            return start + randbelow(width)\n        raise ValueError(\"empty range for randrange()\")\n    if step > 0:\n        n = (width + step - 1) // step\n    elif step < 0:\n        n = (width + step + 1) // step\n    else:\n        raise ValueError(\"zero step for randrange()\")\n    if n <= 0:\n        raise ValueError(f\"empty range in randrange({start}, {stop}, {step})\")\n    return start + step * randbelow(n)\n\ndef randint(a, b):\n    return int(random()*(b-a+1) + a)\n\ndef uniform(a, b):\n    return random()*(b-a) + a\n\ndef randbelow(n):\n    return Math.floor(random()*n)\n\ndef choice(seq):\n    if seq.length > 0:\n        return seq[randbelow(seq.length)]\n    else:\n        raise IndexError()\n\n
+# unlike the python version, this DOES build a range object, feel free to reimplement\ndef randrange():\n    if arguments.length is 1:\n        return randbelow(int(arguments[0]))\n    start = int(arguments[0])\n    stop = int(arguments[1])\n    if arguments.length < 3:\n        step = 1\n    else:\n        step = int(arguments[2])\n    width = stop - start\n    if step is 1:\n        if width > 0:\n            return start + randbelow(width)\n        raise ValueError(\"empty range for randrange()\")\n    if step > 0:\n        n = (width + step - 1) // step\n    elif step < 0:\n        n = (width + step + 1) // step\n    else:\n        raise ValueError(\"zero step for randrange()\")\n    if n <= 0:\n        raise ValueError(f\"empty range in randrange({start}, {stop}, {step})\")\n    return start + step * randbelow(n)\n\ndef randint(a, b):\n    return a + randbelow(b - a + 1)\n\ndef uniform(a, b):\n    return random()*(b-a) + a\n\ndef randbelow(n):\n    return Math.floor(random()*n)\n\ndef choice(seq):\n    if seq.length > 0:\n        return seq[randbelow(seq.length)]\n    else:\n        raise IndexError()\n\n
 
 However you obtain the two RapydScript-NG files, you need to make the following changes: