Bug 977: -T / --init-errors-fatal to process all rules

Have -T / --init-errors-fatal process all rules so that it's easier
to debug problems in ruleset. Otherwise it can be a lengthy fix, test
error cycle if multiple rules have issues.

Convert empty rulefile error into a warning.

Bug #977
Correct flow memory usage bookkeeping error

Fix bug 1321 where flow_memuse was incremented more on allocation than
free.
ipv6: check for MLD messages with HL not 1

MLD messages should have a hop limit of 1 only. All others are invalid.

Written at MLD talk of Enno Rey, Antonios Atlasis & Jayson Salazar during
Deepsec 2014.