fix x2sqz build failure related to goto->goto change
A recent change to allow models to run a 'goto' tags into each other did not label complex line structures in a way assumed by some functions.
A 'Line' block should only be the first block in a complex line. Any follow on segment should be a 'Branch'. This MR fixes the goto-goto fix to follow that rule.
Closes #268 (closed)
Edited by Erik von Reis