gringo/clingo 4.2.1
  * fixed bug in simplification of aggregates
  * fixed bug with raw strings in macros
  * fixed compilation issues with older glibc versions
  * fixed output for enumeration of cautious consequences
  * fixed bugs in clasp library
    * fixed race in parallel model enumeration
    * fixed incremental optimization
    * fixed cleanup up of learnt constraints during incremental solving
  * workaround for libstdc++'s bad choice for hash<uint64_t> on 32bit arches
gringo/clingo 4.2
  * added clingo 
    * supports very flexible scripting support
    * can cover iclingo and oclingo functionality now
  * added stack traces to lua error messages
  * added support for incremental optimization
  * improved python error messages
  * renamed gringo.Function to gringo.Fun
  * removed luabind dependency
  * removed boost-python dependency
  * consistently use not instead of #not as keyword for negation
  * fixed translation of conditions in head aggregates
  * fixed replacement of constants
  * fixed grounding of recursive head aggregates
  * fixed translation of head aggregates
  * fixed show statements for CSP variables (condition was ignored)
  * fixed plain text output of body aggregates
  * added a ton of new bugs
gringo 4.1
  * added scripting languages python and lua
  * added -c option to define constants
  * added constraints over integer variables
    * linear constraints
    * disjoint constraints
    * show statements for constraint variables
    * (experimental and subject to change)
  * improved translation of disjunctions
  * fixed include directives
  * fixed preprocessing of definitions
  * fixed lparse translation of optimization constructs

