Merge pull request kind2-mc#659 from abdoo8080/boolector

Add support for Boolector as a backend engine for Kind2.

Release v1.2.0

Merge pull request kind2-mc#447 from kind2-mc/develop

Docker and travis tweaks, interpreter fixes

Merge pull request kind2-mc#415 from mebsout/develop

Merge with master

correct version number

Correct bound for non constant array sizes

Merge pull request kind2-mc#367 from mebsout/develop

Improvements in parsing and flags

Fail if we use --arrays_rec with a solver other than CVC4

Updated version number for release