Output all current stacked messages, total and exit the program

If there is no error, exit with 0, else exit with 1.

Property definitions

nitc $ ToolContext :: quit
	# Output all current stacked messages, total and exit the program
	#
	# If there is no error, exit with 0, else exit with 1.
	fun quit
	do
		check_errors
		errors_info
		if error_count > 0 then exit(1) else exit(0)
	end
src/toolcontext.nit:186,2--194,4