heur-ma-potential: Refactoring.

Merge branch 'refactor' into lightweight-protobuf

Merge branch 'lm-cut-inc-cache'

Merge branch 'heur-flow'

third-party: Fixed sumodule rule in Makefile.

ma-search: Fixed testsuite.

Plan cost + plan length are printed.

Fixed receiving messages in blocking mode + richer error messages.

ma-snapshot: Fixed *update* procedure where messages should be ignored.