Investigate parsing time regressions

[phdmakk]

Investigate parsing time regressions encountered with:

ETSI ipv6/mobility/ETSI TS 102 596 - v1.2.0 (2008-04)/IPv6 ATS mob/ttcn3/EtsiAtAtsIpv6/AtsMobility

and possibly others (see report from F. Philipp).

The parsing time for IPv6 has been known to be rather long due to some of the constructs used and the nature of the TTCN-3 syntax in general. Nevertheless, significant improvements have been achieved in the past, reducing the parsing time to 2-3 minutes in such cases (modules of sizes >15KLOC). However, parser updates to include support for recent versions of the standard appear to have introduced regression in regard to the parsing times. Investigate these and see if they can be fixed easily or if new issues need to be filled. This could potentially affect other test suites as well.