Mark BIP62 as withdrawn

All of BIP62's (including the only-new-transactions) are currently enforced as standardness rules, but it seems hard to push it further. Every new type of complex transaction may require new extra rules, and some important types of malleability cannot be addressed by it (for example, a single participant in a multisig spend creating a new signature with a different nonce). It seems wiser to pursue normalized txid or segregated witness-based solutions, which do solve this problem more fundamental

Specification