GROOVY-5898: fix for empty quotes
Merge pull request #213 from jwagenleitner/GROOVY-5898-fix

GROOVY-5898: fix for empty quotes
GROOVY-6217: The Edit command should replace the shell buffer, not append.
minimal refactoring after GROOVY-6217: updated copyright, use power asserts
remove unused files
GROOVY-6223: Inferred type is not stored on pre/postfix expressions