add ASM8_EXPERIMENTAL API + support of PermittedSubtypes attribute
As we discuss, this patch add ASM8_EXPERIMENTAL, i've slighly modified the code you send me because getResourceAsStream can return null and the InputStream as to be closed. BTW, PMD is currently configured to not allow an empty catch even if there is a comment in it, but here the right thing to do if we want still to be 1.5 compatible is to ignore the exception that can be raised by close().
Also because we don't run the tests with --enable-preview, i can not write a test to test that at least a roundtrip works