FEAT: [IA-32] Simple exception handling for Red/System.

Use THROW <integer!> to raise an exception and send back an integer ID. Use [catch] attribut in function's spec block where you want to process the exception. Use system/thrown to read the caught exception ID.

Example:

	foo: func [[catch]][
		print "2"
		throw 10
		print "KO"
	]

	print "1"
	foo
	print "3"
	print ["^/thrown value: " system/thrown lf]

will output:
	123
	thrown value: 10