GROOVY-4993: Implementation of @Memoized annotation and its transformation handler.
GROOVY-4993: @Memoized move from 'groovy.lang' to 'groovy.transform' package. Added check for field with same name is already exists.
GROOVY-4993: Forgot to remove the old version @Memoized from 'groovy.lang'.
GROOVY-4993: Added handler for abstract methods and methods that return void.
GROOVY-4993: Added annotation parameters for control of the cache (implementation through memoizeAtMost, memoizeAtLeast and memoizeBetween).
GROOVY-4993: Added more tests.
Merge pull request #154 from bura/ft-memoized-annotation

GROOVY-4993: Implementation of @Memoized annotation and its transformation handler.