1. Timetick test could fail with uptime > 115 days. Thresholds are
double type, so it's safe to put a large number even for 32bit systems.
2. Add a test based on an invalid bug report, worthy anyway.
This patch tries to detect and output nicely multi-line strings. This
method is broken by design; only a count of double-quotes and escapes
could work in every situation.
Only multi-line string test for now (regression test), counter rollover
tests planed with my snmp_counters_new branch.
NB: 64bit counters are broken in NetSNMP::agent from NetSNMP version 5.4.1
and lower, but might come in handy one day