Added unit tests showing that GC'ed SoftReferences are not cleanup from memoize caches
Fixed cache's SoftReferences instantiation in order to register them in a ReferenceQueue
GROOVY-6072: "String | []" is converted to a ClassExpression at semantic analysis
GROOVY-6078: Null safe navigation broken with maps/lists in CompileStatic mode
GROOVY-6061: Subscript assignment not working if the RHS is a VariableSlotLoader
GROOVY-4485: enum does not support default map constructors (minor refactor - delay implicit map constructor addition until a later phase to minimise interactions with other AST transforms)
GROOVY-6082: GroovyResultSet not updateable for Prepared Statements
Merge pull request #128 from luque/memoize-cleanupcache-bugfix

[GROOVY-5948]  memoizeAtLeast and memoizeBetween don't cleanup garbage-collected SoftReferences
deactivated tests because they are successful only sometimes on the build server
GROOVY-5445: Make @Delegate delegate to inherited property accessors
GROOVY-5211: Method dispatch error with @Delegate
minor refactor
travis ci test