fix for #564.

Get rid of the hash table, and use a single-one_time_alloc'ed array for
pattern id assignment.
Minor fixes against the last set of patches for #564, 565, 581 + fp automation.

Rename struct DetectFigureFPAndId_t_ to DetectFPAndItsId_ and move it's
definition from inside the function where it's used to the global namespace,
as requested on #suricata.

Rename DetectEngineContentModifiedBufferSetup to DetectEngineContentModifierBufferSetup.

Also rename DetectFigureFPAndId() to DetectSetFastPatternAndItsId().

Updated DetectSetFastPatternAndItsId() to not exit on failure and return error.
Live rule swap logs added to report SigLoadSignatures() failure. Also set
thread_closed flag on exit for live swap thread.
After some discussion we decided that var declarations inside a for statement are not in line with our coding style. So removing a bunch. Decision was not unanimous ^^.