[preview] mpm optimization v0.35

Clean up of https://github.com/inliniac/suricata/pull/1214

Mostly commit cleanup, reshuffling, message rewording.

Prscript:
- PR build: https://buildbot.openinfosecfoundation.org/builders/inliniac/builds/81
- PR pcaps: https://buildbot.openinfosecfoundation.org/builders/inliniac-pcap/builds/81

cc: @ken-tilera
Interestingly I found a problem here. Sometimes sids is already set. This was leading to a memory leak as we lost the pointer. However it also seems that the sids arrays are different.

So somehow we have multiple patterns in the parray that set the same id in the pid_pat_list.

Any idea @ken-tilera ? @poona ?