Made the CTR mode RFC 3686 compliant (increment then ...

Made the CTR mode RFC 3686 compliant (increment then encrypt) by adding the LTC_CTR_RFC3686 mode flag to ctr_start(). Also fixes to SOBER/RC4 for valgrind users, F8 chaining speed ups, and a bunch of other fixes. ETA on v1.15 is about 2 weeks.