Upgrade to ASM 7.1

    new constant Opcodes.V13 for Java 13
    small optimizations in asm.Type
    check signatures in CheckMethodAdapter.visitLocalVariable
    refactor unit tests to use Arrange-Act-Assert pattern

    deprecations
        deprecate ClassReader.b
        deprecate ASMifiable and Textifiable (replaced with ASMifierSupport and TextifierSupport)
        move deprecated Remapping*Adapter classes to new asm-deprecated.jar
        delete asm.util.Printer buf and appendString (were previously deprecated)

    bug fixes
        317863: Remapper logic for InnerClasses attribute is wrong for method-local Java classes
        317866: Expanded frames result in incorrect types for primitive arrays of more than seven dimensions
        317868: IllegalArgumentException at Frame.getAbstractTypeFromDescriptor on class name with parentheses
        317869: CheckClassAdapter requires non-null ClassVisitor that returns non-null MethodVisitor