paypro: fix server hooking for self-signed paypro testing.
paypro: more server info in validation.
paypro: try to find existing tx proposals.
paypro: drop existing txp check.
paypro: create real paypro txs. start potentially adding more merchant data to notifications.
paypro: add fetchPaymentTx, use for form validation. improve css selection.
paypro: remove old code.
paypro: maintain received payment requests.
paypro: deal with cached payment requests properly.
paypro: refactor cached payment requests.
paypro: cached payment requests. validation.
paypro: misc work.
paypro: fix endianess. fix fields. fix elements in a messy way.
paypro: show untrusted certs.
paypro: all working except for value input.
paypro: total now working.
paypro: remove debug code.
Revert "paypro: remove debug code."

This reverts commit 019283e04cb6b25f6431cb56f02618c6d9e7fe90.
paypro: remove temporary xhr shim.
paypro: fix script buffers.