Changelog for Groovy 2.2.0-rc-2

Bug

[GROOVY-6080] - IncompatibleClassChangeError: the number of constructors during runtime and compile time
[GROOVY-6390] - Super constructor calls are made using MOP with @CompileStatic
[GROOVY-6401] - @CompileStatic type inference bug with overridden methods: causes GroovyCastException at runtime
[GROOVY-6402] - @CompileStatic causes null-safe operator to call method twice