GROOVY-6120: VerifyError if field is used in @Category
   * do not allow usage of instance fields or properties in a class annotated with @Category
   * make @Category compatible with @TypeChecked and @CompileStatic
removed the wrapper task, as it is no longer necessary starting with Gradle 1.7, see:
http://www.gradle.org/docs/1.7-rc-1/release-notes#generate-gradle-wrapper-files-without-touching-your-build-script
Updated wrapper jar, so that the installation via Gradle Wrapper is multi process safe. see:
http://www.gradle.org/docs/1.6/release-notes#installation-via-gradle-wrapper-is-now-multi-process-safe
fixed package declaration, updated copyright
fixed package declaration
moved to the directory matching the declared package
fixed package declaration
GROOVY-6226: Configure Gradle Eclipse plugin for groovy-core

Part 1: Most subproject now seem to work in Eclipse, but the main project still does not
GROOVY-6232: make diamond operator usage pass always in GenericsType#match
GROOVY-6233: don't use GroovyObject to look for unmatched constructor.
GROOVY-6233: fix list literal assignment check to super class
GROOVY-6233: fix unit test for new error message
GROOVY-6233: Fix TupleConstructor and EnumCompletionVisitor not being compatible with @CompileStatic
GROOVY-6237: remove some usages of isUsingGenerics
GROOVY-6242: Improve pre/postfix expression type inference for number types
GROOVY-6243: Fix multiple assignment semantics in @CompileStatic
Merge pull request #173 from melix/GROOVY-6120

GROOVY-6120: VerifyError if field is used in @Category
GROOVY-6244: GroovyConsole should display simple messages too
Make addErrorAndContinue use a SyntaxException for improved error reporting in groovy console
GROOVY-6244: Add newline for SimpleMessage