Refund related registers preservation is not checked in reserve contract

[kushti]

Only in refund related actions preservation of R5 & R6 (refund related) registers is checked. So it is possible to e.g. init or cancel refund on redeeming a note!

So there is need to check such registers!

Alternatively, we may exclude refund actions at all, and so to refund it will be needed to issue a note and then redeem it! (and there will be the same delay after #7 fix implemented)