Partial wallet rescan

Hi all,

Before starting to implement a patch for a specific need, I would like to be sure that it was not written already and available somewhere. This list is probably my best chance.

I would like to add an optional parameter <block_heigh> to "-rescan", from which the rescan would then start. When performing the wallet rescan, everything before the block number <block_heigh> would be ignored. Thus, it would do pretty much the same thing as the wallet birthday mechanism (which relies on nTimeFirstKey), the difference being that the point in time where to start would be *explicitly* given by the user, at launch time, on the command line. Another possiblity is to provide as parameter a time stamp instead of a block height; the interesting part for me is that anyway that information is explicitly provided by the user.

Regards,

Jeremie