Release 1.2.7

Release 1.2.7

* Slightly reduce weights of rules with high FP rate
* Add workround for rspamd-1.3
* Fix possible FP in TRACKER_ID rule
* Simplify MISSING_MIMEOLE rule
* Add workaround for gmime CTE stupidity
* Fix mime headers processing
* Fix false positive URL detections in text parts
* Fix Exim shutdown patch
* Enable workaround for exim mailbox format
* Backport shingles static test
* Fix levenshtein distance calculations
* Fix max_train setup in ANN module
* Fix redis structure by adding {NULL, NULL} member
* Fix build with unmodified LibreSSL opensslv.h
* Repair optional dependencies
* Really skip filters in case of pre-result set
* Restore the intended pre-filters behaviour
* Fix ipv6 mask application

Signed-off-by: Vsevolod Stakhov <vsevolod@highsecure.ru>